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PLANT : 

MAINTENANCE 

MANUAL 



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UNIVERSITY 
OF FLORIDA 
LIBRARIES 




Digitized by the Internet Archive 
in 2013 



http://archive.org/details/plantmaintenancOOclem 



PLANT MAINTENANCE MANUAL 



PLANT MAINTENANCE 
MANUAL 



By 

Edward J. Clement 

Technical Editor 
MILL & FACTORY 

and 

Carl C. Harrington 

Editor-in-Chief 

MILL &. FACTORY 



BOOK DIVISION 
CONOVER-MAST PUBLICATIONS, INC. 

New York Chicago 



ENGINEERING 

SCIENCES 

LIBRARY 



Copyright, 1949, by 
CONOVER-MAST PUBLICATIONS, INC. 

All Rights Reserved. This book or any part 
/hereof may not be reproduced in any 
form without permission oi the publisher. 



PRINTED IN THE UNITED STATES OF AMERICA 



PREFACE 



The purposes of this book on the maintenance of plant equipment are three-fold. 
Yet they all lead to one goal— that of helping to reduce the costs of maintaining a 
manufacturing enterprise. 

One aim is to present the fundamentals for maintaining many kinds of apparatus 
found in most industrial plants so as to prolong their life and usefulness. 

Another is to emphasize the importance of preventive maintenance in modern 
industrial enterprises in lowering repair and other service charges. 

The third objective is a hopeful attempt to impress on manufacturers and their 
machine or product designers the necessity for building "simplicity of maintenance" 
into their products. 

This last aim closely affects plant operating and maintenance men because it will, 
in the end at least, be of advantage in lowering maintenance costs just as effectively 
as does the adoption of efficient maintenance practices. 

If this point were fully appreciated by the manufacturer, he would make his equip- 
ment as easy and economical to maintain as possible. There would seem to be a 
product sales point of high merit. 

Preventive maintenance, the second goal, makes it possible to detect— and thus 
anticipate— possible mechanical or other operational failures. Periodic inspections 
are a vital element in forestalling troubles. But, naturally, the frequencies of, or 
specific time schedules for, inspections vary considerably since they depend upon 
the kind of apparatus or devices used and upon the operating, and often the climatic 
conditions. Here, therefore, experience of the plant maintenance men is usually the 
best guide for such examinations. Nevertheless, and wherever possible, generally 
accepted and recommended practices in those respects are presented as starting 
points or bases. 

Systematic maintenance of plant equipment helps to prevent damage to, and 
costly repairs of, plant equipment. Proper maintenance, too, helps to keep plant 
equipment in a state of high performance and thus reduces interruptions to produc- 
tion operations and services. So, fundamental practices in maintaining many kinds 
of plant equipment are presented. Obviously, it would not be advisable in a book 
of reasonable size and length to include every different kind of machine, piece of 
apparatus or tool used in a plant. Representative kinds of equipment, therefore, have 
been selected to cover the needs of the average plant. 

Most manufacturers issue detailed instructions on the care, operation, maintenance 
and repair of their own equipment. These instruction books, service manuals, techni- 
cal handbooks, and the like are extremely valuable and should be obtained and 
followed. For, after all, should not the manufacturer be the best authority on the 
servicing of his products? Also different techniques are usually required to maintain 
and repair the various makes of equipment. In addition, some devices are inherently 
more complicated than others and thus require considerable detailed data on 
maintenance. 

It is also essential to remember to exercise, at all times and on all kinds of equip- 
ment and operations, the usual safety precautions, especially in handling dangerous 
or harmful materials. 



PREFACE 



The data and other material in this book are based on the many maintenance 
manuals that ran as an editorial part of the regular monthly issues of MILL & FAC- 
TORY of Conover-Mast Publications, Inc. The gratifying reception accorded these 
manuals led the authors and the publisher to incorporate in book form much of the 
material that appeared in those manuals. Tables and other pertinent data have been 
brought up to date with new information. 

The facts have been obtained through the cooperative courtesy of many hundreds 
of leading manufacturers in the country. Without their helpful information and their 
welcome advice and criticisms, this book would not have been possible. 

Credit, too, must go to the many trade associations, industry groups and technical 
societies who freely and kindly gave permission to include valuable and authoritative 
data of theirs in this book. 

THE AUTHORS 



VI 



CONTENTS 

CHAPTER PAGE 

1 LIGHTING EQUIPMENT 1 

2 INDUSTRIAL WIRING 9 

3 ELECTRIC MOTORS 20 

4 PORTABLE ELECTRIC TOOLS 29 

5 TRANSFORMERS 38 

6 INDUSTRIAL CONTROLS ^ 48 

7 SWITCHING EQUIPMENT 61 

8 LEATHER BELTS 73 

9 RUBBER BELTS-FLAT AND V 85 

10 TRANSMISSION CHAINS 96 

1 1 GEAR DRIVES 108 

12 PLAIN BEARINGS 120 

13 BALL AND ROLLER BEARINGS 129 

14 WIRE ROPE 138 

15 CHAIN AND ELECTRIC HOISTS 148 

16 INDUSTRIAL CONVEYORS 160 

17 PORTABLE CONVEYORS AND ELEVATORS 173 

18 INDUSTRIAL POWER TRUCKS 185 

19 ROOFS AND FLOORS 198 

20 PUMPS 210 

21 VALVES 222 

22 TRAPS AND STRAINERS 233 

23 FIRE EXTINGUISHERS 245 

24 AIR COMPRESSOR EQUIPMENT 258 

25 HEATING EQUIPMENT 270 

26 AIR CONDITIONING EQUIPMENT 281 

INDEX 293 

vii 




CHAPTER J 



LIGHTING EQUIPMENT 



The proper and adequate maintenance of 
lighting equipment is essential to effective op- 
erations, to sound industrial economics, and 
to efficient working conditions for personnel. 

Surveys have shown that modern lighting- 
maintenance procedures can provide as much 
as one-third more useful light from an exist- 
ing system than if hit-or-miss practices are 
used. 

For example, one reliable study showed 
that the illumination in a plant was only about 
50% of the available useful light output. Loss 
of light output came from the following causes: 
dead lamps, 15%; dark and dirty walls, 10%; 
and dirty lamps and reflectors, 25%. Proper 
maintenance could restore useful light to 
100% of capacity. 

In another case study, this one involving a 
fluorescent lamp installation, it was found that 
the average value of illumination maintained 
by haphazard methods was only some 65% 
of the total light output possible. Effective 
cleaning of the lamps and reflectors to re- 
move dirt and dust raised the useful light 
some 18%. New lamp and ballast replace- 
ments brought the usefulness of the lighting 
facilities back to 100%. 

Proper maintenance, then, consists of the 
regular cleaning of the lighting equipment 
and the prompt replacement of burned-out 



lamps. Repainting of walls and ceilings, pref- 
erably in light tones, is another factor. Clean- 
ness of ceilings is particularly important, of 
course, where indirect lighting systems are 
used. Keeping up proper voltage conditions 
is also essential. 

Frequent cleaning of lamps and reflectors 
is a most economical way of maintaining a 
high level of useful illumination, as has been 
shown. A common method for establishing a 
suitable cleaning schedule is by checking the 
illumination periodically with a light meter. A 
drop in illumination to 75%, or certainly 66%, 
of total useful light might serve as a signal 
for starting cleaning operations. 

Convenient access to lighting fixtures makes 
maintenance much easier. 

Illuminating Terms 

CANDLE— Unit of luminous intensity, the pri- 
mary standard for which is The International 
Candle. 

CANDLEPOWER - Luminous intensity of light 
source in a given direction, expressed in 
candles. It represents light density in that di- 
rection. 

FOOT-CANDLE -Unit of illumination and 
measure of density of light falling on a sur- 
face at a point one foot from, and on a plane 
perpendicular to, it. One foot-candle equals 



PLANT MAINTENANCE MANUAL 



one lumen per square foot of area. Foot- 
candle readings are usually measured by 
means of a light meter. 

ILLUMINATION -^ Density of the luminous flux 
on a surface as the result of light falling on 
that surface. 

LUMEN — Unit of luminous flux or quantity of 
light. It can be used to express the total out- 
put of a light source or of a point source in 
any solid angle, or the light absorbed, re- 
flected or transmitted. 

Installation Hints 

Trained illumination engineers are available 
from local utility companies, electrical distrib- 
utors, or lamp manufacturers. They should be 
consulted freely regarding equipment and 
layout. 

Here are a few general suggestions re- 
garding lighting installations: 

a. Make a careful study of lighting re- 



quirements and select proper types of 
fixtures and sizes of lamps to do the job 
efficiently. Modern production requires 
illumination values as recommended for 
good current practices. See "Levels of 
Illumination" table. 

b. Lay out distribution circuits so that they 
will not be too long. Use large enough 
wire to keep voltage drop in line under 
2%. 

c. Lay out lamp spacing and mounting 
heights to provide adequate illumination 
at all points. Avoid "roller coaster" type 
of distribution. Uniform illumination should 
be provided over entire working area 
Maximum to minimum should not exceed 
20%. 

d. Make ample use of supplementary 
lighting to give increased illumination 
where needed. Watch out for glare and 
annoying shadows. 



FUNDAMENTALS 

OF FILAMENT AND 

FLUORESCENT LAMPS 



FLUORESCENT LAMP 



INSIDE OF TUBE 

COATED WITM FLUORESCENT 

MATERIAL 



INCANDESCENT LAMP 



FILAMENT 




MERCURY-^ 

SPACE FILLED WITH 
A RARE GAS AND 
MERCURY VAPOR-" 



CATHODE / BASE 

COATEO I l PINS 
WITH 



GAS 



LEAD-IN 
WIRES 



STEM 
PRESS 



EXMAUST 
TUBE 




HIGH- POWER AUXILIARY 



LIGHTING EQUIPMENT 



COMMON TYPES OF FILAMENT AND MERCURY FIXTURES 



FIXTURE 



LAMP 



APPLICATIONS 




GLASSTEEl DIFFUSER 



FILAMENT - clear; 
up to 1000 w. 
MERCURY - 
400 w. 



One of the most satisfactory of the industrial units 
for filament lighting. Glare is reduced by the glass 
globes. Cleaning and relamping require removal of 
the bowl. 




HJGH BAY FIXTURE 



FILAMENT - clear; 
up to 1500 w. 
MERCURY - 
400 w. 



For general illumination from high bay mounting. 
May give undesirable glare. When mercury lamp is 
used, lamps are generally mounted alternately with 
filament lamps. Easy to maintain. 




FILAMENT - clear; 
up to 1500 w. 
MERCURY - 
400 w. 



For general illumination from high bay mounting. 
Maintenance, cleaning, and relamping are fairly 
simple and easy. 



PRISMATIC GLASS 




FILAMENT - 
silvered bowl; 
up to 1000 w. 



A fully indirect type of lighting fixture of particular 
use in offices. Requires a more expensive lamp. Easy 
to maintain. 



SILVERED BOWL 
REFLECTOR 



& 



MERCURY- 400 w. 
FILAMENT - several 
such as 3-150 w. 



FILAMENT AND 
MERCURY COMBINATION 



For general plant illumination where a high quality 
light is required. Gives approximately daylight color- 
ing. Enclosing globe and the several lamps make 
maintenance rather difficult. 



COMMON TYPES OF FLUORESCENT FIXTURES 



FIXTURE 


LAMP 


APPLICATIONS 


OPEN-END INDUSTRIAL 


Generally 2 or 
more - 40, 100 w. 


General industrial illumination. Used to form con- 
tinuous lighting strips. Smaller sizes available for sup- 
plementary lighting near workmen. Easy to maintain. 


CLOSED-END INDUSTRIAL 


Generally 2 or 

more - 20, 40, 100 w. 


General illumination. Also good for supplementary 
lighting. Can be fitted with a louver to reduce direct 
glare. Easy to clean and relamp. 


CONCENTRATING 
REFLECTOR 


Generally 1 lamp 
to a reflector — 
20, 30, 40, 100 w. 


Where a narrow concentration of illumination is de- 
sired, such as inspection, fine bench work, etc. Some- 
times two lamps are mounted together to form a pair. 



Note: Recessed types of units, such as troffers in ceilings, are likewise being used extensively in industry. 

3 



PLANT MAINTENANCE MANUAL 



LAMP LIFE 

In the case of fluorescent lamps, consider- 
able variations may be found in various in- 
stallations because of the differing operating 
conditions. An important variable in this re- 
spect is "the number of starts per hour of 
lamp operation." Frequent starts naturally 
shorten the life of lamps in comparison with 
cases where the starts are fewer. 

Other factors which affect average life of 
lamps are voltage, temperature, and wave 
form. 



Group Replacement 

Group replacement does not mean neces- 
sarily the replacing of all lamps in a plant at 
one time. Any given area may be designated 
as a unit for group replacement — a certain 
number of bays per day, for instance. After 
a particular bay has been maintained com- 
pletely, it would not be visited for replace- 
ment until the life of the lamps in it had again 
reached 70% of average life. 

Times set for group replacement should be 
made definite multiples of cleaning intervals, 



MORTALITY 

CURVE 

FOR 

FLUORESCENT 

LAMPS 


100 






90 

oW 

z 
5 70 

§60 

|so 

-■40 
-30 

§20 

ae 

£10 














































































































































































































































































































°l 


) M)20304OSOt07Oa09OiO0IIOI2OI30l4OI50 
PER CENT OF AVERAGE LIFE 


LAMP REPLACEMENT RATE 

Expected Lamp Renewals 
per time period (month. — 


Number of lamps times the average 
burning hours per time period 
(month, week, etc.) 


week, etc.) 








Rated average lamp life in hours 



REPLACEMENT OF LAMPS 

Two general methods of lamp replacement 
are by individual lamp or by groups of lamps. 

Individual replacement is usually preferred 
where there are relatively few lamps in an 
area and when the unit cost of the lamps is 
high. Mercury lamps with their high output 
and cost come in this class. 

Where unit costs are low and the number 
of lamps in a section is large, it is usually 
found that it is more economical to leave the 
replacement of individual lamps until, say, 
70% of the average life of all lamps in that 
area has been reached. In other words, group 
maintenance is practiced. 

Fluorescent lamp installations are advan- 
tageously kept up by the group plan. In this 
connection a few outages of fluorescent 
lamps are not necessarily annoying, espe- 
cially where no-blink starters are used. Fila- 
ment lamps, too, may be maintained by the 
group method except those of high light out- 
put, which should be handled individually. 



which should preferably be two or three times 
as frequent as replacement. In this way re- 
flectors can be cleaned when new lamps are 
being installed. 

Early burn-outs can be replaced by the 
cleaning crews. Special markings on those 
lamps allow their replacement at regular 
group-replacement periods. These marked 
lamps can be re-used for other early burn- 
outs. This temporary use of these marked 
lamps permits taking full advantage of the 
group plan. 

CLEANING MATERIALS 

Soap and water, plus rags, can work won- 
ders in cleaning lighting equipment. 

There are also many cleaners and deter- 
gents that are entirely suitable for cleaning 
lamps and fixtures. In most cases the strength 
of a cleaner, like an alkali detergent, will not 
affect such surfaces as porcelain-enameled, 
mirror-glass and prismatic glass reflectors. 
Aluminum reflectors, however, must be han- 
dled differently since the metal is likely to be 



LIGHTING EQUIPMENT 



attacked by the alkali. Either neutral deter- 
gents or special wax or wax-emulsion clean- 
ers have been developed for removing dirt 
from that metal. 

In the case of fluorescent lamps, care 
should be taken not to stick the base end in 
water, as water may seep into the base. An- 
olher "don't" is — Do not immerse the base 
of a fluorescent tube in a strong cleaning 
chemical as it might loosen the base from the 
tube. 



WHEN 
CLEANING 


LOOK 
FOR 


Glassware 


Breaks, cracks 


Reflectors 


Damage 


Sockets 


Breaks, looseness 


Switches 


Breaks 


Fittings 


Rust, looseness 


Electrical 
connections 


Looseness 





Two-Man Crew Uses Ten Easy Steps 
In Cleaning By Step Ladder 

1. Man with stepladder places 
it under fixture and mounts 
it. 

2. He removes lamps and re- 
flector,- hands them to man 
on floor. 

3. Man on floor passes a clean 
reflector up to man on lad- 
der. 

4. Ladder man sets the cleaned 
reflector in place in fixture. 

5. Floor man cleans lamps and 
hands them to the man on 
ladder. 

6. Ladder man reinstalls lamps 
and sees that the fixture 
works. 

7. Man on ladder descends 
and moves ladder to the 
next fixture. 

8. Meanwhile floor man washes 
and dries the first reflector. 

9. Man on floor hands cleaned 
reflector to the man on 
ladder. 

10. Cleaning crew repeats 
these steps throughout en- 
tire area. 




EQUIPMENT MAINTENANCE 

Five Must's of Maintenance — 



UNLESS PROPERLY 

MAINTAINED 

LIGHTING SYSTEMS \ I 

WILL DETERIORATE » "^ 



'- Alb 2 "' 



j\ 



. Clean lamps and fixtures frequently. 



THE COST OF \ 

SYSTEMATIC CLEANING/ 
IS A SMALL PART / 

OF THE TOTAL COST / 
OF OPERATING 
THE OUTLET. 




paint walls and ceilings regularly. 
3. Replace burned-out lamps promptly. 



Keep proper circuit voltages. 



5. Establish a definite maintenance 
program. 



PLANT MAINTENANCE MANUAL 



TROUBLE SHOOTING 
Incandescent Lamp Equipment 



Symptom and Cause 



Remedy 



Lamp out, but still good — 




Lamp loose 


Tighten in socket. 


Connections loose or 


Secure terminals, repair 


broken 


wiring. 


Dim burning — 


Increase voltage, or match 


Low voltage 


lamp rating to it. 


Short life - 


Reduce voltage, or match 


High voltage 


lamp rating to it. 


Incorrect lamp 


Replace with correct lamp. 


Extreme vibration 


Install shock absorber. 


Breakage — 




Contact with water 


Use enclosed fixture. 


Bulb touching fixture 


Straighten socket or use 




correct size bulb. 



Mercury Lamp Equipment 


Not starting — 




Loose lamp 


Tighten in socket. 


End of life 


Replace lamp. 


Low voltage 


Increase voltage. See that 




line is connected to 




proper transformer tap. 


Faulty wiring 


Check wiring. Tighten 




connections. 


Fluctuating voltage 


Check line voltage for sev- 




eral days. Dips of 10% 




or more may cause lamps 




to go out. 


Going out frequently — 




Faulty wiring 


Check wiring and tighten 




connections. 


Objectionable 




stroboscopic effect — 




Cyclic flicker 


Add incandescent lamps to 




system. 




Connect fixtures in stag- 




gered order on a three- 




phase supply. 



Fluorescent Lamp Equipment 



Flashing on and off — 




End of life, if old lamp 


Replace lamp. 


Possible fault of lamp 


Replace lamp, check lamp 


or holders 


holders. If blinking con- 




tinues, investigate fur- 




ther. 


Faulty starter 


Replace starter. 


Low ballast rating 


Check ballast and replace 




if necessary. 


Low circuit voltage 


Check voltage and correct 




if possible. 


Loose contacts 


See that lamps are securely 




seated and holders 




rigidly mounted. 



Symptom and Cause 



Remedy 



No starting effort, or 




slow starting — 




End of life 


Replace lamp. 


Defective starter 


Replace starter. 


Incorrect wiring 


Check wiring and make 




proper corrections. 


Low line voltage 


Check voltage and correct 




if possible. 


Air leak in lamp 


Replace lamp. 


Low ballast rating 


Check ballast. 


Open electrode circuit 


Replace lamp. 


Possible open circuit 


Test lamp in another 




circuit. 


Ends of lamp remain 




lighted - 




Faulty starter 


Replace starter. 


Incorrect wiring 


Make proper corrections. 


Low ballast rating 


Replace ballast. 


Flicker, swirl, flutter — 




New lamp may flicker 


Usually clears after short 


when first placed in 


operation. Turn on and 


service 


off a few times. 


End of life, if old 


Replace lamp. 


lamp 




Possible lamp fault 


Replace lamp. If it still 




flickers, investigate fur- 




ther. 


Defective starter 


Replace starter. 


High voltage starting 


Check voltage. 


End blackening — 




Dense at one end, or 




both - 




End of life 


Replace lamp. 


Within 1" of end - 




Mercury deposit at 


Should evaporate as lamp 


ends 


is operated. 


Early in life — 




Defective starter 


Replace starter. 


High or low voltage 


Keep voltage within range. 


Loose circuit contacts 


See that lamps are se- 




curely seated and rigidly 




mounted. 


Improper ballast 


Use approved ballasts of 




correct rating. 


Decreased light output — 




Low circuit voltage 


Check voltage and correct 




if possible. 


Dust, dirt on lamp, fix- 




ture, walls, ceiling 


Clean. 


Radio interference — 




Radio too close to 


Move aerial or radio 9 or 


lamp 


10 ft. from lamp. Shield 




aerial lead-in wire and 




provide good ground. 


Line radiation and 


Use line filter at lamp or 


feedback 


fixture. 


Noise from ballast — 




Slight hum is inherent 




in ballast 




If objectionable 


Mount ballast on soft 




rubber. 




Replace ballast, if too 




noisy. 



LIGHTING EQUIPMENT 



REACHING LIGHTING EQUIPMENT 



WHAT TO USE 


HEIGHT OF 


MOUNTING 




Up to 12 ft. 


12 to 18 ft. 


18 to 30 ft. 


Above 30 ft. 


c* 























































































STEPLAODER — can be equipped 
with special clips and hooks 
to hold spare lamps and 
cleaning rags. 



TELESCOPING PLATFORM - can 
reach almost any height, yet 
is quite small in size when 
it is nested. 




CRANE — convenient in high 
bays, where available; some 
times an auxiliary platform is 
used. 





STRAIGHT LADOER-can be 
readily modified or braced to 
meet mounting conditions of 
reflectors. 



CROW'S-NEST LADDER - where 
aisles permit passage of truck, 
fixtures over machines are 
reachable. 




RELAMPING BRIDGE - where 
cranes are in continuous use, 
or on monorail where no 
cranes are used. 




PORTABLE PLATFORM-de- 
signed to roll through aisles 
and straddle the machinery 
between aisles. 




DISCONNECTING HANGER - 
permits fixture to be lowered 
to the floor for safe and easy 
cleaning. 




CAT WALK OR TRUSS - in high 
bay installations where 
equipment is mounted within 
reach of cat walk. 



PLANT MAINTENANCE MANUAL 



LEVELS OF ILLUMINATION - 
GOOD CURRENT PRACTICE 



Footcandles 
Maintained 
in Service 
Assembly: 

Medium 20 

Medium fine 50 

f'"e ......' 100** 

Extra fine 200** 

Automobile Manufacturing: 

Assembly Line 100** 

Frame Assembly 30 

Body Manufacturing- 
Parts 30 

Assembly 30 

Finishing and Inspecting 200** 

Chemical Works: 

Hand Furnaces, Boiling Tanks, Stationary Driers, 

Stationary and Gravity Crystalizers 5 

Mechanical Furnaces, Generators and Stills, Me- 
chanical Driers, Evaporators, Filtration, Me- 
chanical Crystalizers, Bleaching 10 

Tanks for Cooking, Extractors, Percolators, Ni- 

trators. Electrolytic Cells 20 

Drafting Rooms: 

Prolonged Close Work, Art Drafting, and Design- 
ing in Detail 50 

Elevators— Freight and Passenger 10 

Forge Shops 10 

Garages— Automobile: 

Storage 10 

Repair Department and Washing 50 

Glass Works: 

Mix and Furnace Rooms, Pressing and Lehr, Glass 

Blowing Machines 10 

Grinding, Cutting Glass to Size, Silvering 30 

Fine Grinding, Beveling 50 

Etching, Decorating, Polishing and Inspecting 100** 

Hangars— Airplane: 

Storage 10 

Repair and Maintenance 50 

Ice Making— Engine and Compressor Room 10 

Inspection: 

Medium 20 

Medium Fine 50 

Fine 100** 

Extra Fine 200** 

Locker Rooms 1° 

Machine Shops: 

Rough Bench and Machine Work 20 

Medium Bench and Machine Work, Ordinary Au- 
tomatic Machines, Rough Grinding, Medium 
Buffing and Polishing 30 

Fine Bench and Machine Work, Fine Automatic 
Machines, Medium Grinding, Fine Buffing and 
Polishing 100** 

Extra Fine Bench and Machine Work, Grinding— 

Fine Work 200** 

Offices: 

Bookkeeping, Typing and Accounting 50 

Conference Rooms — 

General Meetings 30 

Stairways 5 

Desk Work- 
Intermittent Reading and Writing 25 

Prolonged Close Work, Computing, Studying, 

Designing, Reading Blueprints and Plans.... 50 



Footcandles 
Maintained 
in Service 

Filing and Index Reference Finding 30 

Lobby 10 

Mail Sorting 30 

Reception Rooms 10- 

Stenographic Work 50 

Vault 20 

Packing and Boxing 10 

Paint Shops: 

Dipping, Spraying, Firing, Rubbing, Ordinary 

Hand Painting & Finishing 20 

Fine Hand Painting and Finishing 50 

Extra Fine Hand Painting and Finishing (Auto- 
mobile Bodies, Piano Cases, etc.) 100** 

Plating 10 

Power Plants, Engine Room, Boilers: 

Boilers, Coal and Ash Handling, Storage Battery 

Rooms 5 

Auxiliary Equipment, Oil Switches, Transformers, 

Engines, Generators Blowers, Compressors 20 

Switchboards and Meters (Control Room) 30 

Receiving and Shipping 10 

Sheet Metal Works: 

Miscellaneous Machines, Medium Bench Work, 
Punches, Presses, Shears, Stamps, Spinning, 
Welders 30 

Tin Plate and Similar Inspection 50 

Stairways 10 

Storage Battery Manufacturing: 

Molding of Grids 20 

Storage and Stock Rooms: 

Rough Bulky Material 5 

Medium 10 

Fine Material Requiring Care 90 

Structural Steel Fabrication 10 

Testing: 

Rough 20 

Fine 30 

Extra Fine Instruments. Scales, Etc 100** 

Toilets and Wash Rooms 10 

Upholstering— Automobile, Coach, Furniture 30 

Warehouse 5 

Welding: 

General Illumination 20 

Supplementary Illumination 1000** 

Woodworking: 

Rough Sawing and Bench Work 20 

Sizing, Planing, Rough Sanding, Medium Quality 
Machine and Bench Work, Gluing, Veneering, 

Cooperage 30 

Fine Bench and Machine Work, Fine Sanding and 

Finishing 50 

** Supplementary luminaires often are used in combina- 
tion with a general lighting level of not less than 20 
footcandles to provide the level required on the work. 
These "Levels of Illumination — Good Current 
Practices" for industrial interior lighting are from the 
"IES Lighting Handbook" published by the Illumin- 
ating Engineering Society. This standard lighting 
guide contains comprehensive and valuable data on 
the subject of lighting. 



Uwfl 8 ^ 



CHAPTER 2 



INDUSTRIAL WIRING 



Electricity is used extensively in most indus- 
trial plants for purposes of light and power. 
Heating, drying, testing and welding are some 
of the other operations commonly performed 
by electrical means. These general fields of 
application cover innumerable different proc- 
esses and services in the modern mill and 
factory. 

Suitable electric current, which is usually 
obtained from some bulk source, must reach 
each light, motor, welder, heater, dryer, in- 
strument and other devices which operate on 
electricity in order that the plant may function 
successfully. It is the distribution system that 
receives the electricity in bulk and delivers it 
to the various machines, lights and other ap- 
paratus that utilize it. 

The successful functioning of many pieces 
of processing and maintenance equipment, 
and of the plant at large, therefore, depends 
upon the effectiveness of the current distribu- 
tion. 

To attain as perfect a performance as pos- 
sible from the electrical system, careful atten- 
tion should be paid to the practical, adequate 
design of the system; the selection of efficient 
equipment from reliable and experienced 
manufacturers; the correct installation of the 
apparatus and devices; and the practice of 
proper preventive maintenance procedures. 

It is, of course, the province of an electrical 



engineer or other electrical expert to design, 
select and install the best system and equip- 
ment for the original job. But it is commonly 
up to the electrical men in the maintenance 
department to see that the installation con- 
tinues to operate efficiently and economically 
and to make adjustments for rearrangements 
in equipment layout as well. 

Proper maintenance of the distribution sys- 
tem contributes to the satisfactory operation 
of the plant. And low maintenance and op- 
erating costs, with a corresponding improve- 
ment in quality of service, are possible, too, 
if a good, safe and adequate system has been 
installed. 

Important Installation Factors 

Some of the important fundamentals to be 
considered in connection with the original 
installation, and in the making of changes 
and extensions thereto, are as follows: 
POWER SUPPLY -characteristics, location in 
relation to buildings and equipment, con- 
venient service entrances. 
ELECTRICAL EQUIPMENT - characteristics, 
types of loads, proper consideration re- 
garding efficient operation and easy ac- 
cessibility for inspection and maintenance, 
ventilation, safety factors, service reliability. 
PROPER VOLTAGES - requirements of indivi- 
dual motors and other units of the power 



PLANT MAINTENANCE MANUAL 



system and the separate needs of the light- 
ing circuits. 

DISTRIBUTION SYSTEM - basic needs, effi- 
cient design, area to be covered, sufficient 
and economical locations of distribution 
centers, as short circuits from distribution 
centers as possible, provisions for enlarge- 
ment and shifting of equipment. 

WIRING — use of approved methods and de- 
vices, conductors of sufficient current- 
carrying capacities, adherence to the 
National Electrical Code and to local 
codes and regulations. 

Distribution Systems 

As already noted, it is the function of the 
distribution system to carry the current from 
the service entrance or the switchboard to 
each device, machine or other piece of equip- 
ment that uses electricity. 

Distribution systems, therefore, comprise 
far more than the wire and cable. They in- 
clude conduits, tubing, raceways, wireways, 
busways, switchboards, panelboards, control 
and protective equipment, cabinets, trans- 
formers, capacitors, junction boxes, cutout 
boxes, insulators, supports, wiring devices, 
accessory fittings and other items. 

Accessory fittings for outlet boxes, for ex- 
ample, consist of connectors, bushings, coup- 
lings, elbows, lock nuts, reducers, enlargers, 
etc. 

Wiring devices comprise switches, outlets, 
caps, plugs, connectors, attachment plugs, 
lamp sockets and the like. 

MAINTENANCE OF DISTRIBUTION 
SYSTEMS 

The upkeep of the distribution equipment 
and devices is as important to the success 
of the electrical system as the original selec- 
tion of the right kind of apparatus. 

As previously said, one of the best ways to 
keep down maintenance costs is to select 
well-designed equipment. For low-cost main- 
tenance it is also necessary that the apparatus 
be installed properly. Accessibility of vulner- 
able parts is another important element. 

Switchboards, circuit breakers, busways, 
and other similar distribution items should be 
located where they are not subject to accum- 
ulations of dirt, dust, lint, etc., or too close to 
travel lanes where they would be subject to 
damage from pedestrian traffic, industrial 
trucks, cranes and other vehicles, or where 
exposed to corrosive and moist -atmospheric 
conditions. 

General maintenance practices for distri- 



bution systems require periodic and system- 
atic inspections. Some of the conditions to 
be looked for are as follows: 

a. Exposed live parts and other potential 
danger spots. 

b. Mechanical damage to, and lack of 
proper protection of, conductors and 

their insulation. 

c. Subjection of conductors to damage be- 
cause location along traffic aisles and 
adjacent to heavy work areas. 

d. Presence of moisture, condensation, chem- 
ical fumes and other detrimental condi- 
tions. 

e. Freedom from vibration. 

f. Loose, dirty, damaged or improperly made 
connections. 

g. Proper ventilation of all devices, 
h. Faulty grounding arrangements. 

i. Heating from circuit overloading and from 
external sources of heat. 

Inspections 

If inspections of all cables and wire circuits, 
connections and fittings have not been made 
for some time, a complete thorough examina- 
tion of the system should be undertaken. Sub- 
sequent inspections should be made as often 
as necessary — intervals of from six to twelve 
months may prove sufficient depending upon 
local conditions. 

Either repair or replace damaged materials 
and devices immediately. In many cases it 
will be found that replacements are less costly 
in the end than the making of repairs. 

An electrical maintenance shop should be 
equipped with all the necessary meters and 
other measuring and testing apparatus, sol- 
dering tools, insulation strippers, pipe cutting 
and threading tools and other essential sup- 
plies and equipment. The amount of such ap- 
paratus depends, of course, upon the size 
and type of the electrical installations in 
the plant. 

This chapter will deal primarily with the 
industrial wiring methods and materials. 

Safe Procedures 

Safety is a most important consideration in 
all electrical work. Fundamental requirements 
for safe procedures with respect to electrical 
installations are set forth in the National Elec- 
trical Code (NEC). This Code is prepared by 
the Electrical Committee of the National Fire 
Protection Association (NFPA) which "acts 
as sponsor for the project under the rules of 
procedure of the American Standards Asso- 
ciation." 



10 



INDUSTRIAL WIRING 



This Code meets the requirements of the 
National Board of Fire Underwriters and is 
endorsed by such national organizations as 
those mentioned below and others. 

The new 1947 edition of National Electrical 
Code was recently published and may be 
obtained from the National Fire Protection 
Association, Boston, Mass., or from the vari- 
ous offices of the National Board of Fire 
Underwriters. 

Adopted by the NFPA at its 1946 annual 
convention, this new Code supersedes the 
1940 NEC and its amendments. The American 
Standards Association has also accepted it 
as an American Standard. 

Because of the extreme importance of the 
Code, and the opportune timeliness of the 
current issue of the new 1947 Code, consider- 
able reference is made to it in this chapter 
and valuable data used from it. Obviously 
only a few sections of the Code can be 
given here. Reference, therefore, to the com- 
plete Code should be made in all cases in 
order to provide safe installations. All quali- 
fied electrical workers in the maintenance 
department should be familiar with the com- 
plete Code. 

In some areas local laws may vary slightly 
from the NEC in some details. In all instances, 
therefore, local codes and regulations should 
be consulted for any such variations. 

Organizations which supply helpful and 
reliable information on the selection, installa- 
tion, operation and care of electrical appara- 
tus of all kinds include such bodies as the 
American Institute of Electrical Engineers, 
Edison Electric Institute, National Electrical 
Manufacturers Association, American Stand- 
ards Association, Illuminating Engineering 
Society, National Electrical Contractors Asso- 
ciation and the electrical groups and commit- 
tees of the National Fire Protection Associa- 
tion, National Board of Fire Underwriters 
and the Associated Factory Mutual Fire Insur- 
ance Companies. 

Adequate Electric Wiring 

The Industry Committee on Interior Wiring 
Design has made studies regarding the essen- 
tials of interior wiring to provide adequate 
and efficient service. While safety is naturally 
paramount, other factors such as economy 
and flexibility are also considered. 

Each plant, of course, has its individual 
problems that require special study. Regard- 
less of this point, there are several elements 
which are of importance in an industrial plant 
of any considerable size. 



In general, a power wiring installation for 
example may be regarded as adequate when 
the following elements have been given 
proper consideration: 

Safety and reliability 

Avoidance of excessive voltage drops and 
copper losses 

Flexibility for changing locations of equip- 
ment 

Provisions for supplying increased loads. 

Safety and reliability can be attained by 
observing the National Electrical Code stand- 
ards — for example, the matter of conductor 
sizes is most important. 

Between the service entrance and any 
motor, the voltage should not be allowed to 
drop more than 5 per cent. Maintenance of 
this feature will help to insure satisfactory 
operations. 

Since in most plants the changing of motor 
locations is a common occurrence, proper 
provisions should be made for probable shifts 
of equipment. This element of flexibility may 
be obtained by means of wireways which 
carry feeders and motor branch circuits; bus- 
ways which have arrangements for plugging- 
in devices; over-size raceways which antici- 
pate changes in motor sizes,- and, if the 
building is suited to them, under-floor race- 
ways which can supply current to a large 
number of small motors. 




11 



PLANT MAINTENANCE MANUAL 



CONDUCTOR INSULATION 


TRADE TYPE MAX. SPECIAL 
NAME LETTER OPERATING PROVISIONS 
TEMP. 


Rubber-Covered 
Fixture Wire 

Solid or 
Stranded 


RF-64 


60C 
140F 

60C 
140F 

60C 
140F 

60C 
140F 

60C 
140F 

60C 
140F 


Fixture wiring. 
Limited to 300 V. 


RF-32 


Fixture wiring, and as permitted 
in section 3103. 


Rubber-Covered 
Fixture Wire 

Flexible 
Stranding 


FF-64 


Fixture wiring. 
Limited to 300 V. 


FF-32 


Fixture wiring. 


Thermoplastic- 
Covered Fixture 
Wire— Solid or 
Stranded 


TF 


Fixture wiring, and as permitted 
in section 3103. 


Thermoplastic- 
Covered Fixture 
Wire-Flexible 
Stranding 


TFF 


Fixture wiring. 


Cotton Covered, 
Heat-Resistant, 
Fixture Wire 


CF 


90C 
194F. 


Fixture wiring. 
Limited to 300 V. 


Asbestos-Covered 
Heat-Resistant, 
Fixture Wire 


AF 


125C 
257F 


Fixture wiring. 
Limited to 300 V. 


Code Rubber 


R 


60C 
140F 


General use. 


Heat-Resistant 
Rubber 


RH 


75C 
167F 

60C 
140F 

60C 
140F 

60C 
140F 

60C 
140F 


General use. 


Moisture- 
Resistant 
Rubber 


RW 


General use and wet locations. 


Latex Rubber 


RU 


General use. 


Thermoplastic 


T 


General use. 
No. 14 to 4/0 inclusive. 
Open work No. 14 to 
2,000,000 CM. 


Moisture- 
Resistant 
Thermoplastic 


TW 


General use and wet locations. 
No. 14 to 4/0 inclusive. 
Open work No. 1 4 to 
2,000,000 CM. 


Thermoplastic 
and Asbestos 


TA 


90C 
194F 


Switchboard wiring only. 



The rubber insulations include those made from natural and synthetic rubber, 
neoprene and other vulcanizable materials. 

Thermoplastic insulation may stiffen at temperatures below minus 1 0°C \14°F) and 
care should be used in its installation at such temperatures. 

For size of conductors recognized for the various insulating coverings, and for 
construction details, see section 93101. 



12 



INDUSTRIAL WIRING 



CONDUCTOR INSULATION 


TRADE TYPE MAX. SPECIAL 
NAME LETTER OPERATING PROVISIONS 
TEMP. 


Varnished 
Cambric 


V 


85C 
185F 

HOC 
230F 

HOC 
230F 

90C 
194F 


Dry locations only. Smaller than 
No. 6 by special permission. 


Asbestos and 

Varnished 

Cambric 


AVA 


Dry locations only. 


Asbestos and 

Varnished 

Cambric 


AVL 


Wet locations. 


Asbestos and 

Varnished 

Cambric 


AVB 


Dry locations only. 


Asbestos 


A 


200C 
392F 

200C 
392F 

125C 
257F 

125C 
257F 

85C 
185F 

90C 
194F 

90C 

194F 

80C 
176F 


Dry locations only. Not for gen- 
eral use. In raceways, only for 
leads to or within apparatus. 
Limited to 300 V. 


Asbestos 


AA 


Dry locations only. Open wir- 
ing. Not for general use. In 
raceways, only for leads to or 
within apparatus. Limited to 
300 V. 


Asbestos 


Al 


Dry locations only. Not for gen- 
eral use. In raceways, only for 
leads to or within apparatus. 
Limited to 300 V. 


Asbestos 


AIA 


Dry locations only. Open wir- 
ing. Not for general use. In 
raceways, only for leads to or 
within apparatus. 


Paper 




For underground service con- 
ductors, or by special permis- 
sion. 


Slow- 
Burning 


SB 


Dry locations only. Open wir- 
ing; and in raceways where 
temperatures will exceed those 
permitted for rubber-covered or 
varnished cambric-covered con- 
ductors. 


Slow-Burning 
Weatherproof 


SBW 


Dry locations only. Open wiring 
only. 


Weatherproof 


WP 


Open wiring by special permis- 
sion where other insulations are 
not suitable for existing con- 
ditions. 



The supplying of increased loads may be 
provided for by making the service equipment 
feeders and sub-feeders large enough to 
allow for some excess capacity. Another point 
to observe is that the raceways and other 
equipment are large enough to allow for the 
installation of any conductors that may be 



needed to provide an increase in capacity. 

Still another valuable measure is the use 
of sectional types of panelboards with inter- 
changeable units, so that control units of 
larger ratings may be instclled. Distribution 
centers should be so designed that the con- 
trol of additional equipment is possible. 



13 



PLANT MAINTENANCE MANUAL 



WIRING METHODS AND MATERIALS 

The 1947 edition of the National Electrical 
Code has been published as a special cloth- 
bound book designated as Volume V of the 
National Fire Codes. Chapter 3 is titled 
"Wiring Methods and Materials." 

Article 300 of this Chapter gives the gen- 
eral requirements for wiring. Article 310 
covers conductors and will be presented com- 
plete below. 

The conductors normally used to carry 
current are of copper unless otherwise pro- 
vided in the Code. Conductor sizes in the 
Code apply, therefore, to copper. If other 
materials are used, the sizes are changed 
accordingly. Section 3106 of Article 310, for 
instance, notes such variation. 

Conductors - Article 310 NEC 

GENERAL (3101). -The intent and purpose 
of the following rules is to provide that con- 
ductors shall have mechanical strength, in- 
sulation, and carrying capacity adequate for 
the particular conditions under which they 
are to be used. 

The provisions of this article are not in- 
tended to apply to conductors which form 
an integral part of equipment such as motors, 
motor controllers, and the like, or which are 
provided for elsewhere in this code. 

CONDUCTOR INSULATION (3102).-Con- 
ductors shall be insulated, except when un- 
insulated conductors are specifically permitted 
in this code. Conductor insulations as speci- 
fied in the accompanying table may be used 
for any of the wiring methods recognized in 
this chapter, except as otherwise provided 
for in the table or the notes following or as 
otherwise specified in this code. They are 
suitable for 600 volts unless otherwise speci- 
fied. 

(a) TEMPERATURE LIMITATIONS. No con- 
ductor shall be used under such conditions 
that its temperature, even when carrying cur- 
rent, will exceed the temperature specified in 
the table for the type of insulation involved. 

(b) WET LOCATIONS. Insulated conduct- 
ors used underground, in concrete slabs" or 
other masonry in direct contact with earth, 
in wet locations, or where condensation or 
accumulation of moisture within the raceway 
is likely to occur, shall be moisture-resistant, 
rubber-covered (type RW); moisture-resistant, 
thermoplastic-covered {type TW) ; lead- 
covered; or of a type aooroved for the 
purpose. 

Such conductors are not suitable for direct 



burial in the earth unless of a type specifically 
approved for the purpose. 

(c) CORROSIVE CONDITIONS. Conduc- 
tors exposed to oils, greases, vapors, gases, 
fumes, liquids or other substances having a 
deleterious effect upon the conductor or in- 
sulation shall be of a type approved for the 
purpose. 

MINIMUM SIZE OF CONDUCTORS (3103). 
—Conductors, whether solid or stranded, 
shall not be smaller than No. 14, except for 
printing press control circuits; as provided for 
flexible cords in section 4006; for fixture wire 
in section 4142; for fractional horsepower 
motors in section 4312; for cranes and hoists 
in section 6112; for elevator control and 
signal circuits in section 6205; for machine 
tools in section 6721; and for remote-control, 
low-energy power and signal circuits in sec- 
tion 7263. 

STRANDED CONDUCTORS (3104).-Except 
when used as busbars, conductors No. 6 and 
larger, installed in raceways, shall be stranded. 
CONDUCTORS IN MULTIPLE (3105).-Con- 
ductors in sizes 1/0 to 500,000 cm., inclusive, 
may be run in multiple provided they are of 
the same length and have the same circular- 
mil area and type of insulation. Not more 
than three No. 1/0, four No. 2/0 nor five 
Nos. 3/0 to 500,000 cm. conductors, in- 
clusive, may be run in multiple. Except as 
herein provided, conductors shall be run in 
multiple only by special permission or as per- 
mitted, in section 6205. Where conductors 
are run in multiple, they shall be arranged 
and terminate at both ends in such a manner 
as to insure equal division of the total current 
between all conductors that are involved. 

CURRENT-CARRYING CAPACITY (3106).- 
The maximum, continuous, current-'carrying 
capacities of copper conductors are given in 
Tables 1, 2 and 3 (and reprinted herein). The 
current-carrying capacities of aluminum con- 
ductors shall be taken as 84 per cent of those 
given for the same sizes of copper conductors 
with the same kind of insulation. 

Other wiring methods and materials ap- 
proved by the Code and for which safety 
procedures are specified in Chapter 3 of the 
National Electrical Code are as follows: 
Open Wiring on Insulators 
Concealed Knob-and-Tube Work 
Bare Conductor Feeders 
Armored Cable 
Non-Metallic Sheathed Cable 
Service-Entrance Cable 
Non-Metallic Waterproof Wiring 
Non-Metallic Surface Extensions 



14 



INDUSTRIAL WIRING 



TABLE 1 - ALLOWABLE CURRENT-CARRYING CAPACITIES 






OF CONDUCTORS IN AMPERES 


. 








Not Mot 


e Than Three 


Conductors in 


Raceway or 


Cable 








(Bas 


ed on Room 


Temperature o 


30 C. 86 


F.) 








Rubber 




Paper 












Type* 
TypeRW 




Thermo- 
plastic 


Asbestos 


Impreg- 
nated 








Type RU 




Asbestos 


Var-Cam 


Asbestos 


Asbestos 


Site 

AWG 

MCM 




(14-6) 


Rubber 
Type 
RH 


Type TA 


Type 
AVA 
Type 
AVL 


Type 
Al 
(14-8) 
Type 
AIA 


Type A 
(14-8) 
Type AA 


Thermo- 
plastic 
TypeT 

(14-4/0) 


Var-Cam 
TypeV 


Asbestos 
Var-Cam 






TypeTW 




Type 










(14-4/0) 




AVB 








14 




15 


15 


25 


30 


30 


30 


12 




20 


20 


30 


35 


40 


40 


10 




30 


30 


40 


45 


50 


55 


8 




40 


45 


50 


60 


65 


70 


6 




55 


65 


70 


80 


85 


95 


4 




70 


85 


90 


105 


115 


120 


3 




80 


100 


105 


120 


130 


145 


2 




95 


115 


120 


135 


145 


165 


1 




110 


130 


140 


160 


170 


190 







125 


150 


155 


190 


200 


225 


00 




145 


175 


185 


215 


230 


250 


000 




165 


200 


210 


245 


265 


285 


0000 




195 


230 


235 


275 


310 


340 


250 




215 


255 


270 


315 


335 




300 




240 


285 


300 


345 


380 




350 




260 


310 


325 


390 


420 




400 




280 


335 


360 


420 


450 




500 




320 


380 


405 


470 


500 




600 




355 


420 


455 


525 


545 




700 




385 


460 


490 


560 


600 




750 




400 


475 


500 


580 


620 




800 




410 


490 


515 


600 


640 




900 




435 


520 


555 








1,000 




455 


545 


585 


680 


730 




1,250 




495 


590 


645 








1.500 




520 


625 


700 


785 






1,750 




545 


650 


735 








2,000 




560 


665 


775 


840 








Correction Factor for Room Temperature* Over 30 


C. 86 F. 




C 


F 














40 


104 


.82 


.88 


.90 


.94 


.95 




45 


113 


.71 


.82 


.85 


.90 


.92 




50 


122 


.58 


.75 


.80 


.87 


.89 




55 


131 


.41 


.67 


.74 


.83 


.86 




60 


140 




.58 


.67 


.79 


.83 


.91 


70 


158 




.35 


.52 


.71 


.76 


.87 


75 


167 






.43 


.66 


.72 


.86 


80 


176 






.30 


.61 


.69 


.84 


90 


194 








.50 


.61 


.80 


100 


212 










.51 


.77 


120 


248 












.69 


140 


284 












.59 



Underplaster Extensions 
Rigid Metal Conduit 
Electrical Metallic Tubing 
Flexible Metal Conduit 
Surface Metal Raceway 
Underfloor Raceway 
Cellular Metal Floor Raceways 



Wireways 

Busways 

Outlet, Switch, Junction Boxes, 

Cabinets and Cutout Boxes 

Auxiliary Gutters 

Switches 

Switchboards and Panelboards 



Fittings 



15 



PLANT MAINTENANCE MANUAL 



MAINTENANCE OF WIRING SYSTEMS 

The best method for preventing failures 
in the wiring system is to inspect all cables 
and wires periodically. Some of the proce- 
dures given earlier in this chapter apply to 
the wiring arrangements. More detailed 
checks are given here. 

The need for inspecting the wiring circuits 
depends to a large extent upon the amount 
of use to which they are subjected — the more 
continuous use, naturally the more frequent 
the inspections. 

Frequently troubles come from sockets and 
cords. An essential to low-cost maintenance 
then is the original installation of good quality 
wire, devices and fittings, as it is with all 
other electrical equipment. 

Proper Inspections Prevent Troubles 



LOOK FOR DAMAGE TO 
CONDUCTORS BECAUSE OF 


PREVENTIVE MAINTENANCE 
PRACTICE 


Exposed locations (along 
passage and traffic 
aisles, near heavy work 
areas, etc.) 


Provide suitable protec- 
tion for cables. 


Abrasion of cable at end 
of conduit 


Protect cable with insu- 
lated bushing, or with 
tape or rubber pad. 


Carelessness of workers 


Instruct men to watch out 
for nearby cables; also 
not to hang clothes or 
tools on cables. 


Tools, rocks, etc., falling 
on cable 


Bury cable for protection. 


Exposure of cable braid 
to weather 


Apply weatherproof paint 
to prevent drying out. 


Swelling and softening of 
rubber-insulated cables 
from oil 


Protect cables where ex- 
posed to dripping oil 
(cutting oils, etc.), or 
where in contact with 
it. 


Fire in one circuit or 
cable spreading to an- 
other 


Apply fireproof cement or 
tape to short lengths; 
install fire barriers; 
protect circuits so they 
open quickly when 
shorts occur. 


Failure to ground from 
lightning surge on 
cable connected to 
overhead line 


Check size and rating of 
lightning arresters. 
Connect arrester 
ground lead to cable 
sheath. 



Hazardous Locations 

The provisions of Article 500 of the NEC 
apply to locations considered hazardous. 

More than ordinary care should be exer- 
cised, therefore, with regard to the installa- 
tion, operation and maintenance of equip- 
ment to insure safe performance. 



CLASS I LOCATIONS 
Those in which flammable gases or vapors 
are or may be present in the air in quantities 
sufficient to produce explosive or ignitible 
mixtures. 

CLASS II LOCATIONS 
Those which are hazardous because of 
the presence of combustible dust. 

CLASS III LOCATIONS 
Those which are hazardous because of 
the presence of easily ignitible fibers or fly- 
ings, but in which such fibers or flyings are 
not likely to be in suspension in air in quanti- 
ties sufficient to produce ignitible mixtures. 

Overheating 

Excessive over heating from overloading 
and the presence of external sources of heat 
is one of the most serious and common causes 
of damage to insulation. To check overloads, 
hook-on ammeters may be used, thus making 
it unnecessary to disturb connections. To 
determine cable overheating, appropriate 
temperature registering or measuring methods 
are usually suitable. 



CABLE LOCATION 



CAUSE OF OVERHEATING 



All Installations 



High current from: 

Low power factor equip- 
ment. 

Low voltage at receiving 
end. 
Unbalanced currents from: 

Unbalanced loading of 
phases. 

Arrangement of single 
conductor cables in 
group. 



In Racks 
Vertically 



Horizontally — — 
Closely spaced or 
near ceiling 

External heating — 



In Tunnels 



In Underground 
ducts ■ 



Aerial Cables. 



Cable risers 



.Heat rising from lower 

cables. 
.Mutual heating. 

•Confining of heat. 

Adjacent sources of heat or 
poor ventilation or sheath- 
ing. 

Overloading. 
Spacing too close. 

Inadequate air circulation or 
insufficient insulation from 
___ external heat source. 

I Overloading. 
- | In adequate ventilation. 

J Overloading. 

" | Im proper shading from sun. 

Exposure to sun. 
Heated air rising to top of 
conduit. 



16 



INDUSTRIAL WIRING 



TABLE 2- ALLOWABLE CURRENT-CARRYING CAPACITIES 
OF CONDUCTORS IN AMPERES 





(Bated on 


Room Tempi 


noture of 


30 C 86 


F ) 


1 




Rubber 




Thermo- 












TypeR 




plastic 












Type 




Asbestos 




Impreg- 




Slow- 




RW 




Type TA 


Asbestos 


nated 




Burning 




TypeRU 


Rub- 




Var-Cam 


Asbestos 


Asbestos 


Type SB 


Six* 


(14-6) 


ber 


Var-Cam 


Type 


Type 


Type A 




AWG 
MCM 




Type 
RH 


TypeV 


AVA 
Type 


At 

(14-8) 


(14-8) 
Type AA 


Weather- 
proof 


Thermo- 




plastic 




Asbestos 


AVI 


Type 




Type WP 




TypeT 




Var-Cam 




AIA 




Type 




Type 




Type 








SBW 




TW 




AVB 










14 


20 


20 


30 


40 


40 


45 


30 


12 


25 


25 


40 


50 


50 


55 


40 


10 


40 


40 


55 


65 


70 


75 


55 




55 


65 


70 


85 


90 


100 


70 




80 


95 


100 


120 


125 


135 


100 




105 


125 


135 


160 


170 


180 


130 




120 


145 


155 


180 


195 


210 


150 




140 


170 


180 


210 


225 


240 


175 




165 


195 


210 


245 


265 


280 


205 





195 


230 


245 


285 


305 


325 


235 


00 


225 


265 


285 


330 


355 


370 


275 


000 


260 


310 


330 


385 


410 


430 


320 


0000 


300 


360 


385 


445 


475 


510 


370 


250 


340 


405 


425 


495 


530 




410 


300 


375 


445 


480 


555 


590 




460 


350 


420 


505 


530 


610 


655 




510 


400 


455 


545 


575 


665 


710 




555 


500 


515 


620 


660 


765 


815 




630 


600 


575 


690 


740 


855 


910 




710 


700 


630 


755 


815 


940 


1,005 




780 


750 


655 


785 


845 


980 


1,045 




810 


800 


680 


815 


880 


1,020 


1,085 




845 


900 


730 


870 


940 








905 


1,000 


780 


935 


1,000 


1,165 


1.240 




965 


1,250 


890 


1,065 


1,130 










1,500 


980 


1,175 


1,260 


1,450 






1,215 i 


1,750 


1,070 


1,280 


1,370 










2,000 


1,155 


1,385 


1,470 


1.715 






1,405 




Correction 


Factor for Room Temperatures 


Over 30 


C. 86 F. 




C F 
















40 104 


.82 


.88 


.90 


.94 


.95 






45 113 


.71 


.82 


.85 


.90 


.92 






50 122 


.58 


.75 


.80 


.87 


.89 






55 131 


.41 


.67 


.74 


.83 


.86 






60 140 




.58 


.67 


.79 


.83 


.91 




70 158 




.35 


.52 


.71. 


.76 


.87 




75 167 






.43 


.66 


.72 


.86 




80 176 






.30 


.61 


.69 


.84 




90 194 








.50 


.61 


.80 




100 212 










.51 


.77 




120 248 












.69 




T40 284 












.59 





Splices, Joints and Taps 

Among the provisions in the new 1947 NEC 
regarding splices and joints are the following: 

ARTICLE 110 -GENERAL SECTION 1118. 
SPLICES. Conductors shall be so spliced or 
joined as to be mechanically and electrically 



secure without solder and, unless an ap- 
proved splicing device is used, shall then be 
soldered with a fusible metal or alloy or 
brazed or welded. All splices and joints and 
the free ends of conductors shall be covered 
with an insulation equal to that of the con- 
ductors. 



17 



PLANT MAINTENANCE MANUAL 



ARTICLE 300 -GENERAL REQUIREMENTS 
FOR WIRING METHODS, SECTION 3005. 
RUNS CONTINUOUS. Raceways and cable 
assemblies shall be continuous from outlet to 
outlet and from fitting to fitting. Conductors 
shall be continuous from outlet to outlet and, 
except as permitted for auxiliary gutters in 
section 3748, and for wireways in section 
3625, there shall be no splice or tap within 
the raceway itself. 

Splices and taps in underfloor raceways 
shall be made only in junction boxes. In cellu- 
lar metal floor raceways, they shall be made 
only in header access units or junction boxes. 

ARTICLE 362-WIREWAYS, SECTION 3625. 
SPLICES AND TAPS. Splices or taps, made 
and insulated by approved methods, may be 
located within the wireway if they are access- 
ible by means of hinged covers. The conduc- 
tors, including splices and taps, shall not fill 
the wireway to more than 75 per cent of its 
area. 

According to the NEC, "Flexible cord shall 
be used only in continuous lengths without 
splice or tap." 

The other provisions in the Code concern- 
ing splices, joints and taps should also be 
observed. 



Flexible Cords 

The conditions of use and location of flex- 
ible cords are given in Article 400 of the 1947 
National Electrical Code. 

Types and trade names of suitable cords 
are listed in an accompanying table. Current 
carrying capacities of flexible cords, as rec- 
ognized by the NEC, are given in Table 3. 

The minimum size for flexible cords is No. 
18, except that tinsel cords, or cords having 
equivalent characteristics, of smaller size may 
be approved for use with specific appliances. 

If the voltage between two conductors ex- 
ceeds 300, but is not over 600, "flexible cord 
of No. 10 and smaller shall have rubber or 
thermoplastic insulation on the individual 
conductors at least 3/64 inch in thickness, 
unless type S, SO or ST cord is used." 

Trade Names and Type Letters of Flexible 
Cords Approved by the NEC 

Asbestos Covered Tinsel Cord— AT 
Cotton Covered Tinsel Cord— CT 
Rubber Jacketed Tinsel Cord— ATJ, CTJ 
Asbestos Covered Heat Resistant Cord— AFC, 

AFPO, AFPD 
Cotton Covered Heat Resistant Cord-CFC, 

CFPO, CFPD 



TABLE 3 - ALLOWABLE CURRENT-CARRYING CAPACITY 


OF FLEXIBLE CORD IN AMPERES 




(Based on Room Tempera 


ure of 30 C. 86 F.) 






Rubber 


Rubber 


Rubber 






Cotton 




and 


Types 


Types 






Types 




Cotton 


PO, C, 


S, SO, SJ, 


Types 




CFC* 




Typos 


PD, P, 


SJO, SV, 


AFS 




CFPO* 




CT, CTJ 


PWP, 


POSJ 


AFSJ 


Types 


CFPD* 


Siie 




K, E, 




HC 


AVPO 




AWG 


Rubber 


EO 


Thermo- 


HPD 


AVPD 


Asbestos 




and 




plastic 


HSJ 




Types 




Atbottos 


Armored 


Types 






AFC* 




Typos 


Type 


ST, SJT, 






AFPO* 




AT, ATJ 


CA 


SVT, POT 






AFPD* 


27** 


0.5 












18 




5 


7 


10 


17 


6 


17 








12 






16 




7 


10 


15 


22 


8 


15 








17 






14 




15 


15 


20 


28 


17 


12 




20 


20 




36 




10 




25 


25 




47 




8 




35 










6 




45 










4 




60 










2 




80 










*These types are used almost exclusively in 


fixtures where 




they are exposed to high temperatures and 


ampere ratings 




are assigned accordingly. 






* 'Tinsel cord. 







18 



INDUSTRIAL WIRING 



Parallel Cord-PO-64, PO-32, PO 

All Rubber Parallel Cord-POSJ-64, POSJ-32 

All Plastic Parallel Cord-POT-64, POT-32 

Lamp Cord— C 

Armored Cord— CA 

Twisted Portable Cord-PD 

Reinforced Cord-P-64, P-32, P 

Moisture Proof Reinforced Cord-PWP-64, 

PWP-32, PWP 

Braided Heavy Duty Cord— K 



Vacuum Cleaner Cord— SV, SVT 

Junior Hard Service Cord-SJ, SJO, SJT 

Hard Service Cord— S, SO, ST 

Rubber Jacketed Heat Resistant Cord— ASFJ, 

AFS 
Heater Cord-HC, HPD 
Rubber Jacketed Heater Cord— HSJ 
Heat and Moisture Resistant Cord— AVPO, 

AVPD 
Elevator Cable-E, EO 



USE FLEXIBLE CORDS 


DO NOT USE FLEXIBLE 


FOR— 




CORDS— 


a. Pendants 


a. 


As a substitute for the 


b. Wiring of fixtures 




fixed wiring of a struc- 


c. Connection of portable 




ture 


lamps or appliances 


b. 


Where run through 


d. Elevator cables 

e. Wiring of cranes and 




holes in walls, ceil- 
ings or floors 


hoists 


c. 


Where run through 


f. Connection of station- 
ary equipment to fa- 
cilitate their inter- 


d. 


doorways, windows or 
similar openings 

Where attached to 


change 




building surfaces 


g. Preventing the trans- 


e. 


Where concealed be- 


mission of noise or 




hind building walls, 


vibration 




ceilings or floors 



19 




CHAPTER 3 



ELECTRIC MOTORS 



During recent years there have been many 
improvements in motor design and construc- 
tion. Some of these have been the indirect 
effect of the scarcity of materials and the 
increased load factor demanded by motors. 
Other improvements have resulted from the 
need for new types of motors for new types 
of service. All these improvements add up to 
better motors for industry and offer the engi- 
neer a wide selection of prime movers to 
drive his equipment and machines. 

A few of the more important improvements 
available in industrial types of motors are 
enumerated below: 

Advanced design and modern styling. 

Durable and pleasing finishes. 

Reduced weight and simplified design. 

More rugged construction and protection 
from physical damage. 

Smaller size and increased capacity. 

Controlled and positive ventilation for uni- 
form cooling. 

Better heat radiating surfaces. 

Non-sparking fans. 

More widely adjustable and interchange- 
able brackets and shields. 

Better static and dynamic balance and pre- 
cision construction of rotors. 

More types and ratings of explosion-proof 
motors. 



Lubrication improvements include the fol- 
lowing: 

Systems providing measured lubrication. 

More durable bearing design and con- 
struction. 

Easily accessible grease plugs. 

Improved protection of working bearing 
parts against foreign particles. 

Sealed bearings in dust-proof assemblies. 

Improvements in winding are as follows: 

Specially impregnated windings. 

Improved insulation and insulating mate- 
rials. 

Protection against high temperatures, oil, 
dust, etc. 

Resistance to aging and heat shock. 

Control improvements include new elec- 
tronic controls and excitation. 




20 



ELECTRIC MOTORS 



HINTS ON PROPER 

Selection ... Be sure to select the proper 
motor for the job to be handled and for the 
type of electrical power supply available. 
Check nameplate data: 

Horsepower against load requirements. 

Whether rating is continuous or not. 

Voltage against line voltage. 

Frequency against line frequency. 

Speed against that required for job. 

Current against line capacity. 




Type of motor— open, enclosed, etc., tc 

meet the hazards of its surroundings. 
Starting torque. 

Location . . . Install motor where it will be: 
Accessible for servicing. 
Protected against shop hazards. 
Protected from dripping oil, or water, iron 

dust, etc., if motor is open type. 
Permitted free ventilation. 
Removed from radiators, heaters, etc. 
Keep out of explosive atmosphere, unless 

explosion-proof type. 




When lifting a motor with a crane, use 
lifting eye in the housing, or place slings under 
the frame. Do not lift with a sling under the 
shaft. 



NSTALLATION 

Supply Line and Controls . . . Make sure 
supply line provides ample copper to handle 
motor current. 

See that lugs and other terminal connec- 
tions are properly installed. .Check control 
for ample capacity and type. 




See that safety switch and fuses are correct 
rating. 

Locate start-stop button where it will be 
handy to operator. 

Rotation ... If motor is to drive a belt, try 
to arrange rotation so that slack side of belt 
is on top, to provide greater arc of contact 
with pulley. 

Before leads are taped up, block them from 
each other and try the motor (disconnected 
from the load, if possible) for correct rotation. 




Be sure bearings are lubricated before start- 
ing motor. 

Check no-load speed of motor and its 
smooth operation. 




21 



PLANT MAINTENANCE MANUAL 



Bearings . . . Make sure bearings are cor- 
rectly lubricated with the proper lubricant — 
follow the manufacturer's instructions. 

Check operation of motor to be certain that 
the motor is: 

Tight on its base. 

Running smoothly. 

Operating with correct belt tension. 

Check bearings of a newly installed motor 
at frequent intervals after it is first put into 
operation. 




WIRE AND CONDUIT SIZE TABLE 







Number of Conductors in Conduit or Tubing 










Rubber Covered, Types RF-32, R, RH, RW and RU 










Thermoplastic, Types TF, T and TW 










One to Nine Conductors 






Size 




NUMBER OF CONDUCTORS IN ONE CONDUIT OR TUBING 






AWG 
MCM 

18 










1 


2 


3 


4 


5 


6 


7 


8 


9 


Vi 


y 2 


y 2 


y 2 


y 2 


y 2 


y 2 


% 


% 


16 


V2 


% 


y 2 


y 2 


y 2 


y 2 


3 /4 


3 /4 


3 /4 


14 


Vi 


y 2 


y 2 


y 2 


% 


3 /4 


i 


1 


1 


12 


Vi 


Vi 


y 2 


3 /4 


% 


i 


i 


1 


T/ 4 


10 


Vi 


% 


3 /4 


% 


1 


i 


i 


T/ 4 


T/4 


8 


V2 


3 /4 


% 


1 


T/ 4 


T/4 


T/ 4 


T/ 2 


T/ 2 


6 


Vi 


i 


i 


T/4 


T/ 2 


T/ 2 


2 


2 


2 


4 


Vi 


T/ 4 


*T/ 4 


T/ 2 


T/ 2 


2 


2 


2 


2'/ 2 


3 


% 


t/ 4 


1% 


T/ 2 


2 


2 


2 


2y 2 


2y 2 


2 


% 


T/ 4 


T/4 


2 


2 


2 


2% 


2y 2 


2% 


1 


% 


t/ 2 


iy 2 


2 


2y 2 


2'/ 2 


2% 


3 


3 





1 


t/ 2 


2 


2 


2y 2 


2'/ 2 


3 


3 


3 


00 


1 


2 


2 


2'/ 2 


2y 2 


3 


3 


3 


3y 2 


000 


1 


2 


2 


2y 2 


3 


3 


3 


3y 2 


3y 2 


0000 


T/ 4 


2 


2'/ 2 


3 


3 


3 


3y 2 


3y 2 


4 


250 


T/ 4 


2y 2 


2y 2 


3 


3 


3'/ 2 


4 


4 


4'/ 2 


300 


T/ 4 


2y 2 


2y 2 


3 


3y 2 


4 


4 


4y 2 


4y 2 


350 


T/4 


3 


3 


3'/ 2 


3y 2 


4 


4'/ 2 


4'/ 2 


5 


400 


T/ 2 


3 


3 


3% 


4 


4 


4y 2 


5 


5 


500 


t/ 2 


3 


3 


3'/ 2 


4 


4y 2 


5 


5 


6 


600 


2 


3y 2 


3y 2 


4 


4y 2 


5 


6 


6 


6 


700 


2 


3y 2 


3'/ 2 


4y 2 


5 


5 


6 


6 




750 


2 


3y 2 


3y 2 


4'/ 2 


5 


6 


6 


6 




800 


2 


3y 2 


4 


4'/ 2 


5 


6 


6 






900 


2 


4 


4 


5 


6 


6 


6 






1000 


2 


4 


4 


5 


6 


6 








1250 


2% 


4'/ 2 


4y 2 


6 


6 










1500 


3 


5 


5 


6 












1750 


3 


5 


6 


6 












2000 


3 


6 


6 




1 










•Where a 


service run of conduit or electrical metallic tubing does not exceed 5 


feet in le 


ngth 


an 


d does n< 


3t contain more than the equivalent of two quarter bends from end tr 


» end two h> 


lo. 4 


ins 


ulated or 


d one No. 4 bare conductors may be installed in 1-inch conduit or tu 


bing. This 


able 


is 


; rom the 


1947 National Electrical Code. 







22 



ELECTRIC MOTORS 



MAINTENANCE SCHEDULE 



Frequency of inspection depends on the nature of the service and the environ- 
ment under which the motor must operate. The following time suggestions are 
for normal motor operation under reasonably clean factory conditions. 



WEEKLY 



Lubrication 
Sleeve bearings. 

Ball and roller 
bearings 

Cleaning 

Controls 

Brushes 



Check oil level in bearings and see that bearings are running cool 
and that oil rings turn with the shaft. Notice if oil is leaking out 
on the shaft. Add oil if necessary (with motor stopped). 
Check bearing housings with the hand for overheating, rough run- 
ning and vibration. Check for creeping of grease from housings to 
motor or shaft. 

Wipe motor clean. If necessary, blow dirt from motor windings with 
dry air at not over 50 lbs. pressure. See that no moisture or grease 
is getting into motor. 

See that fuses and control equipment is in good condition. Wipe off 
control housing. 

Examine commutator (on d-c equipment) and brushes for possible 
adjustment. Clean if necessary. Do not use emery cloth on commu- 
tators. See that brushes move freely in holders and springs are 
in place. 



EVERY 6 MONTHS 



Lubrication 



Bearing wear... 
Alignment 

Load 

Brushes 

Tightness 

Commutator— 
D-C motors 

Controls 



Check the condition of the grease or oil in bearings. Flush the bear- 
ings and renew the lubricant, if dirt is present, or the lubricant is 
in poor condition. See that protective covers of bearing housings are 
tight. 

Inspect bearings for end play and wear. Check air gap clearance 
with feeler gage at both ends of motor. Keep record of clearance 
values, as these figures are a valuable indication of bearing wear. 
Check tightness of motor base bolts and the correct alignment of 
pulleys or shafts. See if belt-tightening adjustment has motor at 
point of maximum center distance. If so, shorten belt. Check tight- 
ness and operating condition of chains and sprockets, or gears. 
Determine approximate load on motor, if only by means of a clamp- 
type ammeter. Try to keep motors as near fully loaded as possible. 
Check speed of motor. 

Make sure that brushes are not too far worn down and that they 
ride freely in their holders. Check pressure of the brush holding 
spring. When replacing brushes, be sure that high quality brushes 
of the proper grade are used. Tighten brush studs. 
Check motor foot bolts, end-shield bolts, pulleys, couplings and 
journal set screws for tightness. Make sure that guards are in the 
proper position and securely fastened. 

Examine commutator surface for tarnish, high bars, and wear. If 
necessary, clean with a cloth dampened with solvent, or touch up 
with a suitable dressing stone. NEVER USE EMERY CLOTH. 
Controls should be given a thorough check, and contact elements 
dressed or replaced where necessary. 



23 



PLANT MAINTENANCE MANUAL 



ONCE EACH YEAR 



Overhaul 



Insulation 



Commutator- 
D-C motors. 



If possible completely-dismantle motor and give it a thorough clean- 
ing and inspection. Wash winding with a suitable solvent and paint 
winding with a good grade of insulation varnish. Clean out bear- 
ing housings and replenish bearings with fresh lubricant. Inspect 
bearings for wear. Check armature bands and all wiring connections. 
Clean all air passages. 

Test insulation with a megger. If readings are low, bake out wind- 
ings until insulation reading is satisfactory. Minimum reading should 
be about one megohm per 1000 volts. 

Inspect condition of commutator. If spot worn it may be necessary 
to true it up in a lathe. Undercut mica separators if they are high. 



HOW TO SERVICE MOTORS PROPERLY 



CHECKING MOTOR LOAD 




Clamp type ammeter can be used to 
determine motor current. Each lead 
should be checked, to see that load is 
balanced. 



CHECKING MOTOR SPEED 




Using a tachometer to che'ck motor 
speed. A revolution counter and a watch 
serve just as well. 



CHECKING MOTOR CLEARANCE 



CHECKING MOTOR INSULATION 





A feeler gage should be used to check 
the air gap at each end of the motor. 



Megger readings give an accurate indi- 
cation of the condition of the insulation 
in the motor windings. Check values 
between all windings and ground, as 
well as between the windings them- 
selves, when possible. 





mm 



24 



ELECTRIC MOTORS 



HOW TO SERVICE 



MOTORS PROPERLY 



LUBRICATION - SLEEVE BEARINGS 




1 . Stop motor. 




2. Wipe oil filling cup 
and spout of oil can. 




3. Fill to PROPER 
level. 




4. If possible, see that 
oil ring revolves prop- 
erly. 



LUBRICATION - 
Ball and 

Roller Bearings 




1. Stop motor. 




2. Wipe pressure gun 
fittings and relief 
plugs on motor. Wipe 
fitting on grease gun. 



25 



PLANT MAINTENANCE MANUAL 



LUBRICATION - Ball and Roll. 




3. Remove relief plug. 




4. Free relief hole of 
any hard grease. 




5. Apply grease while 
motor is running. 




6« Permit motor to 
run with relief plug 
out until excess grease 
is expelled 




7. Replace relief plug. 




8. Wipe off all ex- 
cess grease. 



CLEANING - 



SLEEVE BEARINGS 




1. Stop motor. 








2. Wipe oil cups and 
drain plugs clean. 



26 



ELECTRIC MOTORS 



CLEANING - Sle. 




3. Drain oil and re- 
place plug. 




4. Fill with light flush- 
ing oil. 




5. Run motor a few 
minutes to flush bear- 
ing. 



If GD 



in 



6. Stop motor and 
drain flushing oil. 



7. Repeat 5 and 6 if 
flushing oil indicates 
excessive dirt. 




8. Replace plug and 
fill to proper level 
with correct grade of 
oil. 



CLEANING - 



Ball and Roller Bearings 




1 . Stop motor and 
wipe bearing hous- 
ings and fittings clean. 




2. Remove pressure 
fitting and relief plug. 
Free any hard grease 
in these holes. 



27 



PLANT MAINTENANCE MANUAL 




3. While motor is run- 
ning, inject grease 
solvent and permit sol- 
vent and thinned 
grease to drain out. 




A. Continue to add 
solvent until it runs 
clear. 




5. Stop motor, re- 
place relief plug and 
fill housing with sol- 
vent. Permit motor to 
operate several min- 
utes. 




6. Stop motor and 
drain solvent. If it is 
not clear, repeat step 
5 until solvent ap- 
pears clear. 





7. Replace plug and 
inject small quantity 
of light oil. Run motor 
a few minutes, then 
drain oil. 



8. Replace plug and 
pressure fitting. Lub- 
ricate with PROPER 
grade of grease, as 
shown under LUBRI- 
CATION. 



MOTOR DATA CARD 
Keep Accurate 
Records for 
All Motors 




28 




CHAPTER 4 



PORTABLE ELECTRIC TOOLS 



A surprisingly large number and variety of 
operations in practically all manufacturing and 
assembly processes are performed with port- 
able electric tools. Drilling, grinding, sawing, 
sanding, screw driving, stud setting, nut run- 
ning, shearing, and cleaning are some of the 
many jobs done by these tools in helping mod- 
ern industrial enterprise keep up the fast pace 
of production operations. 

In addition to being valuable aids to pro- 
duction, portable electric tools are also im- 
portant instruments of maintenance. Plant main- 
tenance crews use them daily in keeping 
equipment in top operating shape, in install- 
ing new service lines, in relocating machines, 
in making repairs to machinery and structures, 
and in doing the innumerable tasks of main- 
taining up-to-the-minute efficient conditions. 

ELECTRIC TOOL POWER 

Portable electric tools are powered with 
direct current, alternating current, Universal, 
and High Cycle motors. 

Non-Universal type motors for specific kinds 
of a-c or d-c current are often provided where 
service requirements make their adoption nec- 
essary, or more economical. 

Universal Motors 

Electric tools equipped with Universal motors 
can be used on either d-c or a-c (up to 60 
cycles) circuits of a given voltage. Common 
voltages are 32, 110, 220, and 250. To avoid 



damage to a tool, voltage variations should 
not be allowed to exceed either plus or minus 
10% of the rated standard. 

Light, compact tools of a wide variety of 
kinds, speeds, and capacities have been de- 
veloped around the Universal motor. 

High Cycle Motors 

High Cycle tools were developed to per- 
form at top efficiency under the heavy loads 
and severe conditions of the continuously 
fast rate of current-day mass production. High 
Cycle motors operate on a 180 cycle, 3 phase 
current, usually 220 volts. 

The motor is of the squirrel-cage, induction 
type which has a rotor and a stator, but no 
electrical connections— brushes and commu- 
tator—between them. 

Since High Cycle motors operate on 180 
cycle, 3 phase current, usually 220 volts, it is 
necessary to change the power supplied by 
power companies. Two methods of making this 
conversion are by the use of a frequency 
changer or a motor (or other prime mover) 
generator set. 

Frequency changers are usually used where 
the primary current is 3-phase a-c of 25, 50, 
or 60 cycles. Motor-generator sets are used 
where the power supply is d-c. However, a-c 
drive is often used in order to get closer con- 
trol of the voltage delivered to the tool. 
Where no electrical supply is available, some 
other kind of mechanical power may be used. 



29 



PLANT MAINTENANCE MANUAL 






«a3=ff 





Tool motors perform best, of course, at their 
rated voltage. What happens when operating 
voltages vary too greatly from that rating is 
told elsewhere. 

For satisfactory tool performance, there- 
fore, it is important that the voltage from the 
frequency changer be regulated to within 8% 
variation. 

Where desired in a High Cycle system, the 
tool motor can be protected against unusual 
overloading by means of a standard-type 
fuse, a time-element fuse, or an overload de- 
vice. 

Electro-Magnet Motivation 

There is a type of portable electric hammer 
which does not have a motor — the hammer 
head being actuated by electro magnets. In 
this tool there are also no gears, shafts, or 
bearings. It operates on alternating current. 




30 



PORTABLE ELECTRIC TOOLS 




31 



PLANT MAINTENANCE MANUAL 



USE, CARE, AND MAINTENANCE 

General maintenance practices are much 
the same regardless of the type of motor drive 
—whether standard a-c or d-c, Universal, or 
High Cycle. There are some differing require- 
ments, however. Procedures regarding brushes 
and commutators, for instance, would not ap- 
ply to High Cycle tools. Also, in the case of 
the electro-magnet hammers there are no mo- 
tors, gears, or bearings. Attention will be 
called to certain other differences, where ne- 
cessary. At all times follow the maker's in- 
structions and recommendations. If consider- 
able repairs are required, send the tool to 
the nearest service establishment of the manu- 
facturer. 

PERIODIC INSPECTIONS 

Periodic inspections help to reduce the cost 
of maintaining portable electric tools. 

Parts that should be inspected are the cable 
and plug, switch, commutator and brushes, 
vent holes and siots, bearings, and chucks. 

The scheduling of inspections depends upon 
the service demands or usage of the various 
tools. Experience, too, is a good judge in de- 
termining inspection intervals. 

For tools that operate fairly continuously 
under dusty conditions — like sanders, saws, 
and grinders — it may be necessary to blow 
out the motor vents every day. Complete in- 
spection of such tools after some 150 to 200 
hours may be sufficient in all but extreme 
cases. 

Tools that are used intermittently and in 
places relatively free from dirt and dust — as 
in the case of most drills, nut runners, screw 
drivers, etc.— require less frequent inspections. 



n 



"BE SURE'S" 
of Correct Care and Use 

BE SURE lo- 
use proper size fool for the job. 
Ground tool before using It. 
Turn off power when tool binds or stalls. 
Keep motor from overheating. 
Pick up and carry tool by the handle only, 
follow manufacturer's recommendations. 
Lubricate properly and adequately. 
Inspect tool frequently. 
Clean tools periodically. 
Keep vent holes open. 
Replace worn brushes promptly. 
Return tool to maker If much repair 
Is necessary. 



Procedures to be followed in cleaning, 
greasing and other maintenance processes 
are given later in this chapter. 

Grounding the Tool 

A portable electric tool should always be 
"grounded" while in use — so BE SURE TO 
connect the ground wire before starting to 
work with it. This precaution is especially im- 
portant when dampness or abrasive dust is 
present. Any permanent ground is satisfactory. 




The, conductor intended for grounding pur- 
poses should be identified to distinguish it 
from other conductors. According to the Na- 
tional Electrical Code color' designation, the 
ground wire is the green one, whether the 
cable is of the three-wire or four-conductor 
system. In some cases a white wire has been 
used. Nevertheless in all cases, it is well to 
label that wire with the word "ground". 

One way to insure use of ground wire is by 
means of three-'prong plugs and receptacles. 

Proper Usage 

The power and overload capacities of the 
motors in portable electric tools exceed ordi- 
nary requirements, but a tool should never be 
overloaded continuously. 




Always use the proper size tool for the job. 
Do not employ larger accessories than those 
called for, no matter what the accessory is. 

In drilling, for instance, it is inefficient to 
use a heavy duty tool on light work. It actually 
takes longer to cut a Va inch hole with a V2 
inch drill. Smaller drills are easily broken in 



32 



PORTABLE ELECTRIC TOOLS 



heavy duty tools because of the weight and 
greater torque. 

If a drill sticks, binds, or stalls, turn off the 
current immediately and work the drill free. 
Never attempt to free the tool while the cur- 
rent is on. 

Cables 

Worn out cables should be replaced. In all 
cases use the right grade of cable and be 
sure that the wire is large enough to carry 
the current without serious loss of voltage. 




This precaution is particularly important where 
long extension cables are necessary. At the 
same time, excessively long lines should be 
avoided as they offer greater chances for 
damage. 

High Cycle wires should be kept separate 
from the other wiring systems and be well 
marked for identification. 

Cable failure is a most common cause for 
a tool not running. Check connection to switch 
and plug, also that part of cable near the 
tool which is subject to constant bending. 

All cable connections and repairs should be 
made in accordance with the approved elec- 
trical codes of the locality. 

Never pick up, handle, or drag a tool by 
its cable. 

Switches 

Switches are subject to severe service and 
to considerable abuse. Reasonable care, 
therefore, should be shown them. Switches 
should not be snapped "on" and "off" unne- 
cessarily. When inspecting switches, blow the 
dust from the terminals. 





Bearings 

Bearings should be inspected periodically 
because worn bearings may cause misalign- 
ment of gears as well as wear on the rotor 
and stator. 

Sealed anti-friction bearings are packed 
with sufficient lubrication to last as long as 
the tool. 

Heating of Motor 

A hot motor may burn insulation and wind- 
ings and cause a short circuit. So don't let 
the motor overheat. If it does get hot, stop it 
and examine it. 




Causes of overheating are as follows-. 

Over loading— from dull tool, too much lubri- 
cant, forcing tool beyond ca- 
pacity. 

Bad brushes— broken, chipped, worn too short, 
stuck in guides, poor spring 
tension. 

Poor ventilation— clogged air holes, grease in 
motor housing, dirt in ventilat- 
ing passages. 

High or low voltage— from poor connections, 
light extension wire, excessive 
variation. 

Brushes and Commutators 

Improper attention to brushes causes more 
trouble and tool failures than any other negli- 
gence. Brushes should, therefore, be inspected 
frequently to see that they are free from dust 
and dirt, that they operate without sticking 
and with proper tension, and that they have 
not worn down too much. 



33 



PLANT MAINTENANCE MANUAL 




34 



PORTABLE ELECTRIC TOOLS 



CONSTRUCTIONAL DETAILS 




PRINCIPAL PARTS 

Motor 


_ . A 


Rru.shfis ond C.ommutotor 


B 


.Switrh 


c 


Tohlfi 


D 


Genrs 


F 


Reorings 


F 


Vpnts 


G 


Chuck 


H 


Piston or Hommer Hend 
Elertro Mognet 


1 
1 



35 



PLANT MAINTENANCE MANUAL 




Replace worn brushes immediately, and do 
not use just any brush or a poor substitute. 
Keep on hand a supply of the right kind of 
brushes. Replacement brushes must be not only 
of correct dimensions but also of the right 
hardness. 

Armature commutators should be inspected 
whenever new brushes are put in as well as 
every time the tool is cleaned or repaired. If 
the surface is uneven, or blackened or burned 
from sparking, the commutator should be re- 
moved and trued up. The same corrective 
measure should be followed if the brushes 
have cut grooves in the commutator surface. 

Use sand paper, not emery cloth, to clean 
commutators. If badly out of round turn down 
on a lathe. 

Shorting 

While a "short" may not prevent a tool 
from operating, it should be detected and 
corrected. 

Shorts may occur at various places such as 
in the plug, the receptacle, the cable, or in 
the tool itself. For detecting a short, a test 
socket and lamp affair or any other conven- 
tional testing device may be used. 




Single phasing of the three-phase High Cy- 
cle motors may be caused by a short which 
makes one phase carry the load. While a tool 
may run on a single phase, it will do so with 
greatly reduced power. When single phasing 
occurs, the tool should be shut off and the 
trouble corrected before the tool is started 
again. 

Chucks 

Chucks should be handled with reasonable 
care and not abused. 



Remove the chuck from the drill spindle only 
with the proper equipment. 

Use a specially fitted wrench or the correct 
size key for tightening the chuck. Do not apply 
a pipe wrench, hammer, or chisel. 




For chucks without keys, use either the gear 
locking pin in the gear case, or hold the lock- 
ing collar behind the chuck. In turning the 
chuck, follow arrow on the sleeve. 

Cleaning 

Portable electric tools should be taken apart 
and cleaned as often as usage of the tool dic- 
tates. In the case of drills, screw drives, etc., 
where working conditions are not necessarily 
dusty, every six months may prove a sufficient 
interval between cleanings. Where tools oper- 
ate under dusty, dirty conditions, cleaning 
should be practiced more often. 



r TROUBLE SHOOTING 1 


TROUBLE 


WHAT TO LOOK FOR 


Dead supply line 


Check fuses. 


Poor contact 
between plug 
and receptacle 


Check for 
loose wires or 
bent prongs. 


Worn or dirty 

brushes 


Check for wear, 
dirt, dust, 
poor contact. 


Broken wires 
in switch, 
cable or plug 


Test with lamp 
and socket, 
metering or 
other standard 
testing device. 


Switch 

out of order 


Look for loose 
connections or 
broken wires. 


loss of power, 
or reduced speed 


Check for open 
or short circuit 
in armature. 


Stator 


Look for 

burned-out coils, 
scorched insulation, 
open circuit, ground. 



36 



PORTABLE ELECTRIC TOOLS 




All grease should be removed. Kerosene 
or other suitable petroleum solvent may be 
used for washing out the old grease from the 
gear case, gears, and bearings. Observe great 
care when using inflammable solvents. 

Tools having shielded bearings, however, 
should not be washed out with a solvent. In 
order not to dissolve the grease in those bear- 
ings, the gear case should be wiped out in- 
stead of washed. 

LUBRICATION 

Adequate and correct lubrication adds Hfe 
to portable electric tools. Be sure to follow 
the manufacturers' recommendations regard- 
ing the right lubricants to use. 



That tools being used constantly require 
more frequent lubrication than those not used 
on high production work is quite obvious. 
Lubricating schedules, therefore, depend upon 
tool usage. 

Tool parts which require lubricating are the 
bearings, gear cases, gears, spindles, chuck 
jaws and other like places. A soft cup grease 
is the most common lubricant for portable elec- 
tric tools. Oil is used, of course, when oiler 
fittings are provided, and in the chuck. 

Different tools may require special lubri- 
cants, and in such cases follow only reliable 
instructions. Greasing requirements of gear 
cases commonly vary from one-half to a little 
over one-half full. 

It is a good plan to grease daily the clutch 
on positive, slip, and kick-out attachments on 
screw drivers and nut runners. 

Proper lubrication with the correct lubricant 
is essential. Too little grease causes wear, 
while too much generates excessive heat and 
may force the grease out through the vent 
holes. 

Sealed anti-friction bearings do not require 
periodic lubrication since they are permanently 
packed with sufficient lubricant. 



37 




CHAPTER 5 



TRANSFORMERS 



As defined by NEMA Standards, a trans- 
former is an electric device, without continu- 
ously moving parts, which by electromagnetic 
induction transforms electric energy from one 
or more circuits to one or more other circuits 
at the same frequency, usually with changed 
values of voltage and current. 

The media of the transfer of energy are 
two circuits, primary and secondary, in a 
common magnetic field. Energy is supplied to 
the transformer through the primary circuit 
and is delivered by the transformer through 
the secondary circuit. 

KINDS OF TRANSFORMERS 

There are several ways of classifying trans- 
formers. According to construction features, 
for instance, two general forms are the shell 
and core types. In the former the coils are 
commonly rectangular in shape, and the iron 
core runs through and around the coils to 
create a shell. The latter kind consists of two 
cores each surrounded by a coil. Yokes join 
the cores together at their ends. 

Another way of considering transformers is 
according to the cooling method — oil and 
air. Water has also been used for cooling, 
but to a limited extent only. 

In liquid immersed types, the windings and 
the cores are mounted in a tank containing 
mineral oil or a special fireproof fluid which 



insulates the transformers and carries off the 
heat to the tank surface. 

Dry type units are kept cool by the natural 
circulation of air. Additional cooling in the 
form of air ducts through the winding may be 
provided for either natural circulation or by 
air blasts. 

Transformers are also classed as to their 
single or polyphase characteristics. 

By usage transformers are considered as 
follows: power, distribution, furnace, bell ring- 
ing and so forth. 

Transformer Usage 

The distinction between power and dis- 
tribution transformers is commonly one of 
capacity or rated kva. Sizes above 500 kva 
are considered as power transformers while 
those of 500 kva and less belong to the dis- 
tribution class. This chapter will treat primarily 
of smaller transformers which are used for 
"distributing power from high voltage lines to 
locations where a lower voltage is required" 

SPECIALTY TRANSFORMERS 

Several kinds of specialty transformers are 
used industrially. One class of specialty trans- 
former is known as the general purpose trans- 
former. It is essentially a dry-'type distribution 
device of all kva ratings 600 volts and less. 
Generally the primary windings of these units 



38 



TRANSFORMERS 



are connected to secondary distribution, cir- 
cuits for the purpose of supplying still lower 
voltage current for lighting purposes and small 
power loads. 

Control Transformers 

General purpose control transformers are 
another of the specialty kind. They are es- 
sentially dry-type control devices which are 
used with their primary windings connected 
to secondary distribution circuits to supply 
still lower voltages to lighting and small con- 
trol loads. 

High reactance control transformers are 
used for operating large bells, chimes, fur- 
nace-damper controls, and valves and relays 
of heating and air conditioning equipment. 
Although of limited power input, they deliver 
greater output than doorbell transformers. 
They are designed to withstand the "short- 
circuiting of secondary terminals without burn- 
ing out or heating excessively" 

Signalling Transformers 

Signalling transformers are small, air-cooled 
transformers, the chief purpose of which is to 
supply low voltage power to signaling sys- 
tems needing more power than can be sup- 
plied by doorbell type transformers. 

Luminous-Tube Transformers 

These transformers are used with luminous- 
tube signs as needed in the sign industry for 
the generally used ranges of tube sizes, lengths 
and brilliancies. 

Ignition Transformers 

Ignition transformers provide a high-voltage 
spark between two electrodes for the ignition 
of fuel and air mixtures in gas and oil burners. 

Doorbell Transformers 

Of limited output, doorbell transformers can 
withstand short circuiting of secondary term- 
inals without heating excessively or burning 
out. 

DEFINITIONS 

Note: All definitions here quoted are National 
Electrical Manufacturers Association (NEMA) 
Standards, which in many cases are identical 
with American Standards. 

Types of Transformers 

AUTOTRANSFORMER-A transformer in which 
part of the winding is common to both the 
primary and the secondary circuits. 

STEP-UP TRANSFORMER -One in which the 
energy transfer is from the low-voltage 
winding to the high^voltage winding. 



ESSENTIALS TO SUCCESSFUL 
OPERATION OF TRANSFORMERS 



PROPER 




DESIGN AND MANUFACTURE 




INSTALLATION AND OPERATION 




CARE AND MAINTENANCE 



39 



PLANT MAINTENANCE MANUAL 



STEP-DOWN TRANSFORMER- Energy trans- 
fer is from the high-voltage winding to the 
low-voltage winding. 

DRY-TYPE TRANSFORMER -One which is 
cooled by the circulation of air and not 
liquid-immersed. 

INDOOR TRANSFORMER- A transformer 
which, because of its construction, must be 
protected from the weather. 

OUTDOOR TRANSFORMER -A transformer 
of weather-proof construction. 

Ratings 

The rating of a transformer or other induc- 
tion apparatus consists of the output together 
with any other characteristics, such as volt- 
age, current, frequency, and power factor, 
assigned to it by the manufacturer. It is re- 
garded as a test rating which defines an out- 
put that can be taken from the apparatus un- 
der prescribed conditions of test and within 
the limitations of established standards. 

RATED KVA OF A TRANSFORMER - The out- 
put which can be delivered for the time 
specified at rated secondary voltage and 
rated frequency without exceeding the spe- 
cified temperature limitations. 

CONTINUOUS RATING OF A TRANS- 
FORMER — The rating that defines a con- 
stant load which can be carried without 
causing further measurable increase in tem- 
perature rise under prescribed conditions 
of test and within the limitations of estab- 
lished standards. 

SHORT-TIME RATING -The rating that de- 
fines the load which can be carried for 
a short and definitely specified time, the 
apparatus being approximately at room 
temperature at the time the load is applied. 

Performance 

EFFICIENCY — The ratio of the useful power 
output to the total power input, 

AMBIENT TEMPERATURE -Temperature of the 
air which, coming into contact with the 



heated parts of a machine, carries off the 
heat. 

Note I — Ambient temperature is commonly 
known as "Room Temperature" in connec- 
tion with air-cooled apparatus not provided 
with artificial ventilation. 

Note II -The NEMA standard specified that 
the standard ambient temperature of refer- 
ence, when the cooling medium is air, shall 
not exceed 40 C. 

DIELECTRIC TESTS - Tests which consist of 
the application of a voltage higher than 
the rated voltage for a specific time and 
designated to determine the adequacy 
against breakdown of insulating material 
and spacing under normal conditions. 

Windings 

HIGH-VOLTAGE AND LOW-VOLTAGE 
WINDINGS — As applied to two-winding 
transformers, the terms are used to distin- 
guish the winding having the greater, from 
that having the lesser, voltage rating. 

PRIMARY WINDING -The winding on the 
input side. 

SECONDARY WINDING -The winding on 
the output side. 

Taps 

A tap in a transformer is a connection 
brought out of a winding at some point be- 
tween its extremities, usually to permit chang- 
ing the voltage ratio. 

Polarity 

The polarity of a transformer is a designa- 
tion of the relation of. the high-voltage and 
low-voltage leads with respect to each other. 
(Polarity is of importance to maintenance men 
when connecting transformers in parallel or 
when banking two or more transformers. The 
marking of the leads helps to make this work 
easy and is usually noted on the nameplate 
or connection diagram of the transformer.) 



ALWAYS PLAY SAFE WITH TRANSFORMERS 

Save your own life and the lives of others—by 
playing safe with transformers. 

Never take chances with transformers by assum- 
ing that they are dead. Before working on them 
be sure that the breaker or switch is open. Also, 
never energize a transformer before making cer- 
tain that "All Is Clear." 



SA/m 
FIRST* 




40 



TRANSFORMERS 



Miscellaneous 

CORE OF A TRANSFORMER - The whole of 
the iron forming the magnetic circuit. 

LAMINATION OF A TRANSFORMER - One 
of the thin sheets of iron or steel which 
form part of the magnetic circuit in the core. 

MAINTENANCE OF TRANSFORMERS 

Instructions for the care and operation of 
transformers depend upon the sizes of the 
units as follows: 

(a) Transformers larger than 100 kva — be- 
low 15,000 volts, and all sizes above 
15,000 volts; and 

(b) Distribution transformers — 100 kva and 
smaller — 15,000 volts and below. 

These latter transformers are considered as 
small distribution transformers and are used 
in very large quantities. Their care and main- 
tenance are much more simple than is the 
case with large units. 

Large distribution transformers— those larger 
than 100 kva below 15,000 volts, and all sizes 
above 15,000 volts — should receive the same 
attention that is given to power transformers, 
as noted in (a) above. 

CARE OF SMALL DISTRIBUTION 
TRANSFORMERS 

(Based on NEMA Specifications) 
Small distribution transformers require very 
little maintenance. Proper location of trans- 
formers for easy accessibility and inspection, 
however, is essential. Adequate ventilation is 
another important consideration. This latter 
point is particularly true in the case of self- 
cooled transformers since the surrounding air 
must carry away the heat. 

For indoor installations, therefore, these 
transformers must be located in rooms which 
are well-ventilated for the escape of heated 
air and the entrance of cool outside air. To 
allow free circulation, transformers should be 
separated from any walls and partitions and 
not less than 12 to 18 inches from each other 
so that free circulation around the tanks is 
possible. 

Handling 

Always exercise care in handling transform- 
ers. If cranes are not available, skids or rollers 
may be used. If large transformers are moved 
by rollers, however, skids should be used so 
as to distribute the load over the base. By 
all means avoid damaging a transformer by 
tipping it over or by injuring the base. 

Jacks or tackles for lifting or moving should 



never be placed under the drain valve or 
other attachments. Neither should transformers 
be moved by grasping them by their leads. 

Mounting 

In pole mounting, hanger irons are often 
fastened to the case before raising the trans- 
former to the cross arm. Elevating is accom- 
plished by attaching the rope to the lugs or 
eye bolts on the side of the case. Lifting the 
transformer a little above the cross arm allows 
it to be lowered so that the hooks engage 
the cross-arm. 

The practice of bolting transformers directly 
to poles is also quite common. 

Storage 

Even though transformers may not be put 
into service for some time, it is advisable 
to set them up in their proper locations and 
fill them with oil, if oil-cooled. If they have 
to be stored before use, they should be kept 
in a dry place where there are no rapid or 
excessive temperature changes. Immersion in 
dry transformer oil is advisable where pos- 
sible. Never use or store transformers where 
corrosive gases like chlorine are present. 

INSPECTION AND INSTALLATION 

Proper installation is a prerequisite for low- 
cost maintenance. So follow manufacturers' 
instructions carefully. 




Before installing, examine transformers for 
indications of rough handling in transit. Manu- 
facturers have tested their transformer thor- 
oughly so that they are in first class condition 
when shipped. Any damage to them, then, has 
doubtless occurred while in transit. 

Moisture lowers dielectric strength and may 
cause transformer failure. If moisture has con- 
densed on the transformers or oil drums, they 
should be allowed to stand until thoroughly 
dry of condensate before opening. 



41 



PLANT MAINTENANCE MANUAL 



In addition to inspection for moisture and 
breakage before placing in service, trans- 
formers having several voltage connections 
should be checked to see that the right con- 
nections have been made for the desired 
operation. Transformers are usually shipped 
connected for maximum voltage. 

Drying Out 

With distribution transformers that are 
shipped in tanks without oil, it is not usually 
necessary to dry them out because the wind- 
ings are specially impregnated. If, however, 
visual inspection shows the presence of mois- 
ture, the transformers should be dried out. 

With transformers shipped with oil in their 
tanks, the oil should be tested according to 
methods given later. If moisture is present, 
the transformers should be dried out. 

Approved methods of drying transformer 
core and coils are of two general kinds — 
drying with the core and coils in the tank 
with oil present or with the oil removed. In 
the latter case the core and coils may or 
may not be in the tank. 

Drying with Oil in Tank 

When drying with oil in the tank, the cur- 
rent is sent through the winding while im- 
mersed. Adequate ventilation is necessary, 
and may be obtained by keeping the top 
open. A short circuit provides the necessary 
current to generate internal heat. Moisture is 
driven from the coils and insulation into the 
oil for removal by evaporation or filtering 
or both. 

Drying with Oil Removed 

With oil removed, moisture can be expelled 
by the application of internal heat, external 
heat or both internal and external heat. 

For the internal heat process, see preceding 
section. This method which is slow and super- 
ficial, should be used only with small trans- 
formers. 

The external heat process consists of heated 



air passed through the ventilating ducts in 
the windings. 

For a more rapid drying process a combi- 
nation of the internal and external heat proc- 
esses can be used. However, when this 
method is employed, technically skilled super- 
vision is required because the amount of 
internal current used must be reduced to pre- 
vent damage to the windings from excessive 
heat. 

Precautions 

In drying without oil, be sure that the tem- 
perature does not exceed 85 deg. C. Ther- 
mometers should be placed at several spots — 
among the coils near the top and screened 
from air currents in the ventilating ducts. At 
first the thermometers should be read every 
half-hour. One thermometer should be located 
so that it can be read without shifting or 
removing it. The other thermometers should 
be placed at the hottest spots, which can 
be determined by shifting the thermometers 
around. 

The increase in resistance method should 
be used for checking temperatures as much 
as possible. Generally insulation resistance in- 
creases gradually until approaching the end 
of the drying period. Resistance measure- 
ments should be taken as close to the same 
temperatures as possible. 

The time required for drying depends on 
the condition of the transformer, the size, 
the voltage and the method used and may 
vary from one to three weeks. 

Constant attention should be given trans- 
formers while drying them out. A good pre- 
caution is to have a chemical fire extinguisher 
or a supply of sand at hand. 

TRANSFORMER FAILURE 

A good indication of a winding failure is 
the noisy expulsion of smoke or cooling liquid 
from the case. When a transformer fails, 
consult the manufacturer and follow his in- 
structions for examination, disassembly, identi- 



BE CAREFUL WITH WORK TOOLS 

Care must be shown in handling tools and 
loose articles when working around a transformer 
in order not to drop anything metallic among the 
windings. Such foreign matter may cause break- 
downs in the transformer. 




42 



TRANSFORMERS 



fication and ordering of repair parts, and 
for cleaning and re-using good parts. Do not 
re-energize the transformer at rated voltages 
because doing so might cause additional in- 
ternal damage. 

When failure occurs, the supply breaker or 
fuse normally disconnects the device from the 
power source. Nevertheless, make sure that 
the transformer is disconnected. Inspect for 
damage to bushings, leads, potheads, dis- 
connecting switches and other parts. Note 
the oil level in all compartments and measure 
its temperature. Look for leakage of liquid. 

For indications of electrical faults, there are 
several tests. One is to take megohmmeter 
readings between the windings and between 
each winding and ground. Another is to check 
the ratios against the nameplate listings by 
applying 250 volts a-c, or less, to the high 
voltage winding. Others are to make resist- 
ance readings of winding connections and 
to test the dielectric strength of the insulating 
liquid. 

If examination shows that the fault lies in- 
side the transformer, go over the interior 
thoroughly. But first remove the liquid, stor- 
ing that from each compartment in a separate 
container. 

Look for damage or for any unusual con- 
ditions. Disconnect all leads, ratio adjusters, 
thermometers and other parts. Remove the 
core and coils and examine for damage to 
them and to the insulation. 

COOLING AND INSULATING MEDIUMS 

Either air or a liquid is the medium for cool- 
ing transformers and the method used gen- 
erally depends upon the size of the trans- 
former and the operating conditions. 

Many small transformers of low voltage are 
cooled by air. These dry-type devices are 
ventilated by natural air circulation or by air 
blasts. Ducts between the coils are often pro- 
vided, especially in air blast units, for the 
flow of air through the coils. 

Transformers which are too large for nat- 
ural cooling are commonly immersed in a 
liquid; some small distribution transformers are 
also liquid-cooled. Mineral oils or non-inflam- 
mable synthetic liquids are used for cooling 
and insulating. The latter go under a variety 
of trade names. 

By convection the liquid absorbs the heat 
from the hot parts of the transformer and 
transfers it to the walls of the tank or the 
housing, from which it is dissipated into the 
air that surrounds the tank. Sometimes special 
cooling arrangements are employed to in- 



crease the exposed surface of the housing. 
Fans are an additional means for increasing 
the effectiveness of the cooling. 

The synthetic liquids are handled in much 
the same way as the mineral oil. Cleanliness 
is always essential. 

Checking the Liquid 

The liquid, which is just as essential a part 
of a transformer as is any other material, 
should be sampled and tested before it is 
placed in the transformer. It should also be 
examined periodically for its condition while 
in service. 




See that dirt and moisture do not get into 
the liquid. Moisture, even in very small 
amounts, and oxidation will spoil the insulat- 
ing or dielectric qualities of the oil. Oxida- 
tion will cause the formation of a sludge. 
Moist air may even be "breathed" into the 
transformer, especially one not in continuous 
service, to condense and drop into the oil. 

Drums containing the liquid should be stored 
indoors or otherwise protected from the 
weather. Containers should be kept tightly 
sealed until the liquid is used. 

Oil containing any moisture should be re- 
treated. 

Sampling Oil 

A large-mouthed glass container with a 
cork stopper is usually employed in sampling 
oil. The bottle must be clean and dry. 

At least a 16 oz. sample should be used 
for dielectric tests; 32 oz. samples, if other 
tests are to be made. Samples should be 
drawn off transformers from the oil sampling 



43 



PLANT MAINTENANCE MANUAL 



valve at the bottom of the tank. Make sure 
that the oil is taken out of the transformer 
bottom, not just from the sampling pipe. 

Before drawing samples, oil in barrels 
should be allowed to settle for at least 8 




hours; for oil in large transformers settling 
time should be a matter of days. Barrel sam- 
ples are taken from the bottom of the drum, 
using a brass or a glass "thief" which must 
also be clean and dry. 

Testing Oil 

Oil of normal dryness when shipped has a 
dielectric strength of 22 kv or higher in the 
standard test cup. If service tests show values 
around' 17.5 kv, or lower, the oil should be 
filtered. Manufacturers of apparatus for test- 
ing and treating oil furnish detailed instruc- 
tions regarding their equipment. 




Filling Transformers 

A transformer should be filled through a fil- 
ter press, using a metal, rather than a rubber, 
hose, If no press is available, several thick- 
nesses of muslin can be used for filtering. The 
muslin must have been thoroughly cleaned 
and dried to make it free of sizing and of 
moisture. 

Filling of transformers may be done either 
before or after positioning. Since the insula- 
tion absorbs some oil, it is often necessary to 
add oil shortly after installation. Furthermore, 
since the oil in the transformer should be 
kept at the normal level, it is usuallv neces- 
sary to add oil from time to time. In handling 
the oil, be sure that no moisture enters the 
transformer. 

In replacing a transformer cover, be sure 
that the gasket is correctly positioned and 
that the cover is bolted securely to the case. 
This precaution is particularly important when 
the transformer is exposed to rain and snow. 

INSPECTION 

Although transformers need much less atten- 
tion in service than most other kinds of elec- 
trical apparatus, they do require a certain 
amount of periodic maintenance. For any neg- 
lect of them may lead to serious troubles. 

In order that transformer equipment will 
give as reliable, trouble-free service as possi- 
ble, a regular schedule of inspections should 
be adopted — and carefully followed. The ex- 
tent and frequency of these preventive main- 
tenance measures depend, of course, on oper- 
ating conditions such as the dirt content of 
the atmosphere, ambient temperatures and so 
forth. 

As pointed out before, distribution and other 
small transformers need less care than the 
larger units. But where a continuous power 
service is required, these small transformers 
should receive more maintenance than instal- 
lations where service is intermittent. Greater 
attention is also justified where apparatus is 
subject to severe overloads or frequent short 
circuiting. 

Trouble symptoms that should be investi- 
gated at once are unusual noises, improper 
oil levels and abnormal temperature increases 
at normal loads. 

Inspection Schedules 

EVERY SHIFT 

Check liquid level gage. 

Watch temperatures— ambient, liquid and 

winding. 

Observe load current on transformer banks. 



44 



TRANSFORMERS 



W" 




e 




Filter Press used 
for filling transformer 



Note voltage, for checking proper tap con- 
nections. 

EVERY 3 MONTHS 

Examine functioning of relays. 

EVERY 6 MONTHS 

Inspect overvoltage protective equipment. 
See that ground connections are in good con- 
dition. 

Special Inspections for Various Kinds of 
Transformers 

Oil-Immersed Liquid Type 

Periodic checks should be made of temper- 
ature and load conditions and of the oil 
level, as determined by operating conditions. 

OIL— Test condition of oil for proper dielec- 
tric strength — Every 3 months. 

MOISTURE — Look under cover to see if con- 
densation is taking place and inspect 
for water in bottom of tank — Monthly 
for the first 6 months, then every 6 months 
thereafter. 

SLUDGE — Drain oil to top of core and check 



above core for deposits of sludge and 
for indications of moisture — At least 
every two years. 

Non-inflammable Liquid Type 

Transformers filled with synthetic non-inflam- 
mable and non-explosive liquid should be 
treated the same as oil-immersed devices. The 
liquid should be kept free of moisture and 
dirt and should be tested periodically, the 
frequency depending, of course, upon the 
operating and climatic circumstances. 

Contamination of the non-inflammable liquid 
with mineral oil should be guarded against 
because the latter affects the characteristics 
of the former. 

Since conlinued exposure to the synthetic 
product can irritate the skin, customary safety 
precautions should be observed in handling it. 
Also subjection to the vapors in poorly venti- 
lated rooms should be avoided. Cleanliness 
among the workers is the first essential. Spe- 
cial gloves also help considerably. Castor oil 
and cold cream have proved to be good neu- 
tralizes of this irritation. 

Dry Type 

Periodic inspections of cooling and insulat- 



ALWAYS READY FOR USE 

Keeping spare transformers ready for immedi- 
ate use is an important preventive maintenance 
practice. Neglect of these units may result in their 
failure in service. 




45 



PLANT MAINTENANCE MANUAL 



TRANSFORMER TROUBLES 





GENERAL 


CAUSES 


HIGH TEMPERATURES 


High ambient temperatures 
Inadequate cooling 
Insufficient liquid 
Obstructed air intake or 

clogged ducts 
Overcurrent 
Overvoltage 
Sludge in oil 


MECHANICAL 


CAUSES 


FRACTURED BUSHINGS 


> Unusual strains on connec- 
tions or terminals 


LEAKAGE 
AT JOINTS 


Loose joints 

Improper assembly 

Clogged threads 

Poor compression of gaskets 


IN WELDS 


Imperfect or broken welds 


MOISTURE 

CONDENSATION 


Insufficient or plugged 

ventilators 
Leaky joints 
Cracked diaphragm 


RUSTING OR 
PAINT WEAR 


Weathering or rubbing 


ELECTRICAL 


CAUSES 


SUSHING 
FLASHOVER 


Dirty bushings 
Lightning 


CORE FAILURE 


Breakdown of insulation 
Foreign metal between 
laminations 


HIGH CURRENT 


Core short circuited or joints 
open 


INCORRECT 
VOLTAGE 


Improper ratio 
Abnormal current voltage 


INTERNAL ARCING 


Faulty insulation 
Low liquid level 


WINDING FAILURE 


Lightning 

Low dielectric liquid 

Overload 

Short circuit 


OIL 


CAUSES 


DISCOLORATION 


Excessive heating 
Winding or core failure 


LOW DIELECTRIC 
STRENGTH 


Condensation 

Leaks around cover and in 
cooling coil 



46 



TRANSFORMERS 



ing liquids are naturally unnecessary with air- 
cooled transformers. 

LOADS AND TEMPERATURES - Check peri- 
odically. 

FANS— On air blast units, check fan operation 
every shift. Lubricate every 12 months. 

CORES AND COILS- Examine, every three 
months at least, for dust accumulations 
in air ducts and on windings and leads. 
If dusty, de-energize the transformer and 
blow out dust with dry compressed air 
at pressures of from 25 lb per sq. in. to 
50 maximum. 

CONTACT SURFACES-When changing taps, 
see that they are clean. 




47 




CHAPTER 6 



INDUSTRIAL CONTROLS 



An electric controller, as defined by the 
National Electrical Manufacturers Association 
standards, is "a device, or group of devices, 
which serves to govern, in some predeter- 
mined manner, the electric power delivered to 
the apparatus to which it is connected." The 
Association further states that "any switching 
device having features intended for the start- 
ing and protection of motors" shall be judged 
to be a motor controller. 

The functions of industrial control appa- 
ratus, therefore, may be those of starting, reg- 
ulating speed, reversing and stopping a motor 
as well as of controlling its frequency and 
length of time of operation. Thus an electric 
controller may comprise anything from a sim- 
ple knife switch to a complicated combina- 
tion of contactors, resistors, relays, switches 
and other devices. 

ELECTRIC CONTROLLERS 

Controllers may be open or enclosed, re- 
versing or nonreversing. Their operation may 
be manual, semi-automatic or full automatic. 
In automatic controllers part or all the basic 
functions are performed by electromagnets or 
solenoids, or by motor-driven, thermal or me- 
chanical arrangements, or by hydraulic or 
pneumatic pressure. 

Operating service duties of controllers are 
continuous, intermittent, periodic or varying. 
Service classifications may be either general- 



purpose or special-purpose. The latter class 
covers controls for cranes and hoists, eleva- 
tors, machine tools and the like. Depending 
upon their types, motors are started on either 
full voltage or reduced voltage. 

Controls are also considered, of course, 
according to whether they are for a-c or d-c 
motors. 

Protection 

Special construction or protection features 
can be supplied for controls which will be 
subjected to unusual operating conditions. The 
following are features of this sort, as defined 
by NEMA standards: 

Dustproof, dust-tight, dripproof, driptight, 
splashproof, watertight, weatherproof, sleet- 
proof, submersible (immersible), gasproof, gas- 
tight, moisture-resistant, acid-resistant, and 
fume-resistant. 

Most motor starters are provided with de- 
vices for undervoltage protection or under- 
voltage release. The former, or low-voltage 
protection, is an arrangement or device which 
opens the circuit upon the reduction or failure 
of the voltage but has to be reclosed by the 
operator. The latter, or low-voltage release, 
is an arrangement or device which opens the 
circuit on the reduction or failure of the volt- 
age but does not prevent the automatic re- 
closing of the circuit upon a return to normal 
voltage. 



48 



INDUSTRIAL CONTROLS 



Overload protection is usually effected 
through the use of relays of a thermal or mag- 
netic type. 

Accessories 

Although not parts of the controller proper, 
certain accessories are used to actuate the 
controller and to give it a flexibility that makes 
possible complicated operating sequences. 
These items include such switches as master, 
push button, drum, pressure, time, float and 
limit, and thermostats. Still other accessories, 
sometimes classed as static, are resistors, rec- 
tifiers, capacitors and transformers. 

Starting Motors 

The simplest way of starting a motor is to 
throw it across the supply line on full voltage. 
This method is commonly used for a-c squirrel 
cage and quite frequently for synchronous 
motors and may be employed with series and 
compound wound d-c motors of low horse- 
power. 

The majority of d-c motors, however, are 
started on reduced voltage. The voltage re- 
duction is accomplished by the introduction 
of resistance in the circuit. 

Regardless of whether starters are of the 
full or reduced voltage type, their operation 
may be either manual or automatic. 

Automatic acceleration of motors is accom- 
plished by time or by current arrangements, 
or by a time-current combination or other 
means. Time-limit acceleration is very com- 
monly employed on many automatic starters 
used for general purposes. The time element 
may be controlled by devices of a mechanical 
magnetic, solenoid, dash pot, motor-driven, 
inducting current decay or other nature. 

Selection of Equipment 

Prerequisites to a good program for main- 
taining electric industrial control equipment 
are the selection of the right apparatus and 



its proper installation. Both factors are also 
essential to safety. 

The selection of apparatus for a specific in- 
stallation depends upon the electric power 
supply available, the machinery to be con- 
trolled and its starting requirements, and the 
surrounding conditions. In regard to the 
power supply the following points must be 
considered.- whether a-c or d-c, and the 
voltage in either case; and if a-c, the fre- 
quency and phase of the circuit. The wire 
system — 2, 3 or 4 wires — and the frequency 
of starts, reversals, time intervals, and the 
like are other influences. 

Some other points to be thought of are 
that all the component parts used should be 
fully integrated and correctly rated for nor- 
mal functioning, that full safety features are 
included, and that any special construction 
requirements to meet unusual service condi- 
tions are observed. These last-named con- 
ditions are shown in list forms. 

In all cases manufacturers of control ap- 
paratus should be consulted for advice and 
recommendations regarding equipment. 

Unusual Service Conditions 
(NEMA Standards IC2-25) 

A. The use of apparatus in cooling mediums 
having temperatures higher than 40 C, or at 
altitudes greater than 6000 feet, should be 
considered as special applications. 

B. There are further unusual conditions which, 
where they exist, should be called to the 
manufacturer's attention. Apparatus for use 
in such cases may require special construc- 
tion or protection. Among such unusual condi- 
tions are: 

1. Exposure to damaging fumes. 

2. Operation in damp places. 

3. Exposure to excessive dust. 

4. Exposure to gritty or abrasive dust. 

5. Exposure to steam. 

6. Exposure to excessive oil vapor 




49 



PLANT MAINTENANCE MANUAL 




50 



NDUSTRIAL CONTROLS 




7. Exposure to salt water. 

8. Exposure to vibration, shocks and tilting. 

9. Exposure to explosive dust or gases. 
10. Exposure to the weather or dripping 

water. 

Installation and Adjustment 

Correct installation of electric industrial 
control apparatus makes maintenance easier. 
All installation work and connections should 
be made in accordance with manufacturer's 
instructions and drawings. 

Be sure that the panel is mounted firmly 
on a flat surface and firm foundation free 
from vibration and in a well ventilated loca- 
tion. Set it up vertically so that contactors 
will open by gravity. 

On open controllers terminals are supplied 
for the connection of the ground wires. Where 
controllers are enclosed, the conduit connec- 
tion to the cases is regarded as sufficient 
protection. 

Each contactor and relay should be ope- 
rated by hand before the power is turned on 
in order to make sure that the moving parts 
work freely. 

Mounting of resistor boxes should be such 
as to permit free ventilation and grids should 



be in a vertical plane. Connections to the 
resistor terminals should be of slow-burning 
or non-inflammable wire. 

Contacts are kept in good condition by the 
opening and closing actions. 

Interlocks should make clean contact when 
closed. The adjustment of electrical interlocks 
is such that they usually make contact at about 
the same time as do the main contactor tips. 
When one contactor of a mechanical inter- 
lock is closed, the play on the other is very 
small. 

Make sure that the interlocks, whether 
mechanical or electrical, are adjusted as de- 
scribed in the manufacturer's instruction book. 

Care should be shown in unpacking new 
equipment because parts of large equipment 
are often tied down or are even shipped 
separately. Any braces or fasteners should be 
removed. Do not overlook any small parts or 
lose them in the packing material. Dirt and 
packing material should be blown out. 

If any surfaces are coated with rust-pre- 
ventive oil or grease, the compounds should 
be removed before putting the apparatus into 
service. However, wiping certain surfaces 
every now and then with a thin, rust-proofing 
oil is a good maintenance practice. 



51 



PLANT MAINTENANCE MANUAL 



MAINTENANCE 



Proper care of electric industrial controls in- 
creases their life and decrease's troubles and 



costly shutdowns. Inspect and service control 
equipment at regular intervals. 



GENERAL INSPECTIONS 

Inspect For — Check — 

Overloading— —Installation to see that loads have not 
been stepped up beyond danger 
point. 

Protection — Condition of fuses, heaters, circuit 

breakers. Make sure ratings are 
correct for load* carried. 

Wear Each switch and unit for cleanness 

and for condition of contacts and 
other parts. 

Safety — — ^— Condition of boxes and interlocking 
safety devices, and gaskets, if any. 

Overheating — Location and load conditions of ap- 
paratus. 



A Winning "Nine" of Maintenance 

Keep equipment clean and dry. 
Operate switches and controls periodically. 
Make sure clearances are normal. 
Replace worn or imperfect parts promptly. 
Clean contacts according to official in- 
structions. 

6. Check contacts for trouble-causing con- 
ditions. 

7. Lubricate regularly, where recommended. 

8. Test handles, blades, crossbars for correct' 
operation engagement and alignment. 

9. Paint boxes and conduits periodically to 
prevent rust or corrosion. 

For the maintenance of industrial control 
equipment, a systematic and competent pro- 
gram should be established. It should include 
both periodic inspections and preventive main- 
tenance measures. 

Two good points to follow in setting up 
this program are: 

1. To list the items to be inspected and 



specify how often they should be 

checked. 
2. To keep on hand an ample supply of 

renewal and repair parts. 
The kind of preventive maintenance needed 
depends a great deal upon the frequency of 
operation of the control equipment. The more 
frequent the operation, the greater the wear 
on the mechanical parts and contacts. Also, 
in controllers that undergo long and continu- 
ous duty, some kinds of contacts may over- 
heat and weld together or the springs may 
lose their temper. 

On the other hand, apparatus that is idle 
for extended periods or is used infrequently 
collects dust and is subject to corrosion— mov- 
ing parts rust, contacts oxidize, and insulation 
absorbs moisture. 

Keep apparatus in proper working condition 
at all times. Pay special attention to equip- 
ment subject to severe duty and exposed to 
extreme conditions. Maintain the supply volt- 




52 



INDUSTRIAL CONTROLS 



age within normal operating limits, and do not 
exceed rated loads. 

Instruct operators to show good judgment 
in handling controls and to refrain from abus- 
ing equipment. For instance, switches should 
be thrown neither violently nor hesitantly. 

Nuts and connection wires on panels and 
resistors should be examined occasionally, es- 
pecially if subject to vibration. Pigtail connec- 
tions should also be observed periodically. 
This latter examination is particularly impor- 
tant where atmospheres are extremely corro- 
sive. Furthermore, where corrosive gases or 
much moisture are present, it is good practice 
to paint control parts from two to four times a 
year, as conditions require. 

Keep Equipment Clean 

Dust interferes with normal operation,- so 
prevent accumulations of dirt, oil, grease or 
water on operating parts of the controls 
Heavy dust on interlocks, for instance, may 
even prevent the completion of the circuit. 

Where dust or dirt has collected on any 
part, remove with a heavy brush or wooden 




scraper. If the dust is dry it can be blown oft 
with compressed air of moderate pressure. 
Be sure there is no water in the air line. 

A cleaning fluid like carbon tetrachloride 
will remove grease, oil or sticky dirt. Do not 
soak parts in the cleaner, and use only enough 
cleaner to loosen grease sufficiently for wiping 
off. For getting into crevices and corners of 
small parts, use a small paint brush which is 
dipped into the cleaning solution. 

TROUBLE SHOOTING 

When troubles occur — and they do happen 
even in the best of installations — it is usually 
desirable, often quite necessary, to correct 
them as speedily as possible in order to save 
valuable production time. 

Inoperative apparatus can be put back into 
service more quickly if the operator is familiar 
with each circuit and with the operation of 
each piece of equipment. Valuable tools in 
this connection are the elementary diagrams 
supplied by the manufacturers of the control 
equipment. Other helpful tools to keep con- 
veniently on hand are portable instruments for 
checking voltage, current, resistance, etc. 

In returning broken or damaged parts to 
the manufacturer, complete information should 
be given concerning Jhe nameplate data, 
operating conditions and the failure. 

When basic causes of trouble are under- 
stood, it is easier to note the symptoms, make 
the repairs, and also to find ways to lessen 
future troubles. 

Details of causes and remedies of various 
troubles will be given later under appropriate 
classifications. 



IF TROUBLE IS 


LOOK FOR 


Failure to Start 


Failure of, or too low, voltage. 


or Operate 


Open overload relay contact. 




Open circuits. 




Blown fuses. 




Broken wires. 




Loose connections. 




Burned out coils, resistors, or trans- 




formers. 




Worn, burned, or corroded contacts 




on switches and accessories. 


Failure to Stop 


Grounds. 




Bad wiring. 




Welded contacts. 




Faulty brakes. 




Shorts in connections. 




Failure of contacts to open. 




Damaged limit switches or acces- 




sories. 



53 



PLANT MAINTENANCE MANUAL 



MONTHLY 
INSPECTIONS 


Magnet Operated 
Devices 


Thermally Operated 
Devices 


Motor Operated 
Devices 


Contactors, Relays, 
Solenoids, Brakes, Etc. 


Overload Relays, 

Temperature Relays, 

Thermostats, Etc. 


Timers, Valves, 
Brakes, Rheostats 


Broken or worn mechanical parts X 


X 


X 


Condition of shunt connections X 


X 


X 


Control circuit condition 


X 




Corrosion of metal parts X 


X 


X 


Dirt or gum accumulations X 


X 


X 


Excess slam on pick up X 






Excessive arcing when opening circuits X 


X 


X 


Excessive heating of parts X 


X 


X 


Excessive noise or vibration X 




X 


Freedom of moving parts X 


X 


X 


Gearing lubrication 




X 


Heating element condition 


X 




Loose connections X 


X 


X 


Oil condition, if oil immersed X 




X 


Proper contact pressures X 


X 


X 


Proper functioning and operation X 




X 


State of arc boxes, chutes or barriers X 






Status of gaskets, if any X 




X 


Voltage of control circuit X 




X 


Water or liquid drip on controls X 


X 


X 


Wear on contacts X 




X 


Wheels and linings on brakes X 









54 



NDUSTRIAL CONTROLS 



Twice Yearly Inspections 

Mechanically Operated Devices 

Inspect mechanically operated master and 
other switches for the following: 
Broken or worn mechanical parts. 
Condition of shunt connections. 
Control circuit condition. 
Corrosion of metal parts. 
Dirt or gum accumulations. 
Excessive arcing when opening circuits. 
Excessive heating of parts. 
Freedom of moving parts. 
Loose connections. 
Lubricate, where recommended. 
Oil condition, if oil immersed. 
Proper contact pressures. 
State of arc boxes, chutes or barriers. 
Status of gaskets, if any. 
Water or liquid drip on controls. 
Wear on contacts. 
Resistors, Rectifiers, Capacitors, Transformers, 
Fuses, Wiring, Etc. 
Inspect for — 

Dirt or gum accumulations. 
Excessive heating of parts. 
Corrosion of metal parts. 
Loose connections. 
Arc Boxes, Chutes or Barriers — Repair or re- 
place if badly damaged or almost burned 
through; tighten loose bolts and screws; ad- 
just moving parts, if necessary. 
Shunts — Look for damage from wear and cor- 
rosion; twist to see if in good condition. 
Interlocks - Make sure that they are adjusted 

according to manufacturer's instructions. 
Push Button, Overload Relay, Contacts — See 

that they function freely. 
Gaskets — Note tears, corrosion, and other 
damage. 

Contacts 
Contacts are the "conducting parts which 
coact to complete or interrupt a circuit." Con- 
tactors are'devices "for repeatedly establish- 
ing and interrupting an electric power circuit." 
Contacts should be worked by hand occa- 
sionally to see that they are in good operating 
condition and that their clearances are normal. 
The condition of the contact surfaces should 
be examined. 

Contacts may be designed to close by a 
pounding, sliding, scrubbing, or rolling action 
— sometimes a combination of them. Contacts, 
therefore, clean themselves to a considerable 
degree. They are closed by hand, electro- 
magnets or solenoids, small motors, tempera- 
ture devices, or air pressure. 

Certain large contacts have separate, 
smaller contacts which save the main ones 



from heavy arcing. These arcing contacts or 
tips are the first to touch in closing and the 
last to separate in opening. 

Contacts and contact tips are made in a 
variety of forms and metals — copper, silver 
and special alloys. Copper is a very common 
metal for tips on power contacts of control 
apparatus. Being a soft metal, however, cop- 
per has low resistance to wear and abrasion. 
Also, copper tends to oxidize when the con- 
tacts are closed for long periods. The oxide 
increases the resistance, thus generating more 
heat to produce more oxide. Small amounts 
of oxide, however, are cleaned off by the 
abrasive action of ordinary closing operations. 

Welding and sticking likewise happen to 
copper contacts under certain conditions of 
high currents. 

It is not necessary to keep the contact points 
smooth. Tips roughened or pitted by ordinary 
arcing will conduct the current satisfactorily. 
However, when contacts are badly pitted or 
burned, they should be replaced or dressed 
up by sandpapering or fling. But never use 
emery or a coarse file. 

Contacts should seat squarely, and contact 
pressures should be maintained. Both the sur- 




face area and the pressure affect contact 
resistance — small areas and weak pressures 
develop heating. Bolts and screws should be 
tight. Furthermore, the tip faces should not be 
lubricated, except in some few cases. Oil will- 
burn and increase the heating and keep the 
contacts from cleaning themselves. 

Silver is also a soft metal and has low resis- 
tance to wear but it has a higher conductivity 
than copper. While silver does oxidize, the 



55 



PLANT MAINTENANCE MANUAL 



oxide coating can be easily broken. Thus 
silver contacts do not require filing. 

Various alloys and combinations of non- 
welding materials are also used in contact 
tips. Gold, platinum, rhodium, palladium and 
some of their alloys can be employed too. 
Recommendations should be sought from man- 
ufacturers regarding applications of contact 
metals. 




Contact Troubles and Cures 



TROUBLE 
Excessive pitting or] 
burning * 



Overheating .., 
Overloading — — 
Oxide formation 



Poor contact 

Weak tip pressure — 
Welding or freezing 



CURE 
• If copper, dress with sandpaper or fine 

file. 
If too bad, replace. 
■ Clean, and tighten loose connections. 
Reduce current,* or use larger device. 
Copper — If slight, mechanical operations 

will break it. Otherwise sandpaper or 

file. 
Silver — Do not file, coating easily broken 

by mechanical operation. 
If excessive, replace. 
.Improve; or use interlock for holding. 
Clean and adjust; or replace. 
Check rating against load. 
Check spring pressure; replace spring, if 

necessary. 
Reduce current. 
Replace with more suitable equipment: 

Use special non-weld tips. 

Install larger device. 



Magnets and Coils 



In magnetic motor controls e'ectromagnets 
or solenoids activate the contacts, relays and 
circuit breakers. In addition they are also used 
to operate trip mechanisms, brakes, interlock- 
ing devices and other items. 

The main difference between a-c and d-c 
magnetic contactors lies in the construction 
of the magnet. The former are made of thin 
steel laminations fastened together, whereas 
the cores of d-c magnets may be made from 
iron or steel bars or plates. 

Since in a-c contactors the magnetic force 
pulsates, the a-c magnets are subject to vibra- 
tion and chatter, which conditions, however, 
may be overcome by proper provisions, such 
as the special mounting of moving parts. In 
case of noisy magnets, check for loose lami- 
nations, broken shading coils and poor core 
seating. If laminated cores become loose, they 
should be restocked and fastened tightly to- 
gether again, or replaced. Magnets must close 



properly to prevent overheating of coils. 

Magnets should be maintained in good con- 
dition, both electrically and mechanically. 
When broken or damaged, they should be re- 
paired or replaced. Examinations should be 
made for corroded contacts and for proper 
air gaps. 

Cleanness and proper ventilation of coils 
are most important. Connections should be 
tight, and at no time should coils be carried 
by their leads. 

Operating voitages should be maintained 
within the allowable limits. Burnt-out coils 
should be replaced. 

Coils which become wet can be baked dry 
in an oven. This baking applies also to coils 
which have been soaked in carbon tetrachlor- 
ide to remove grease or oil. 

If coils are revarnished, use only approved 
insulating paint or varnish. Apply paint when 
the coil is still warm from baking. 



56 



INDUSTRIAL CONTROLS 



TROUBLE CURE 

Coil failure ■ Relocate coils; or use special ones. 

— — Relocate; or furnish special mounting. 
•—Replace, if unusual, or if coils are loose 
or laminations broken. 
Provide special mounting for moving parts. 
— Check voltage, coil rating and application. 
Check for shorted turns; proper closing; 
loose, corroded, or oxidized connections. 
Sluggishness - Clean and adjust. 

Unusual short life of coil-* Check voltage and rating of coil. 
Worn and broken parts — — Replace; and correct cause of damage. 



Excessive vibration 
Noisy magnet 



Overheating 



Shunts 

Controller shunts, which are the flexible con- and flexing. They should be inspected for 

nectors between the moving and stationary fraying, wear, kinks, sharp bends and broken 

parts, are subject to considerable bending strands. 



TROUBLE 
Corrosion or moisture 

damage 
Overheating 



CURE 
Check application. 



Worn, broken or frayed 



Check for correct application or installa- 
tion. 
Replace. 




Interlocks 



"An interlock is a device actuated by the 
operation of some other device with which it 
is directly associated, to govern succeeding 
operations of the same or allied devices." 
They may be electrical or mechanical. (NEMA 
Standards 1C50-102.) These units permit com- 
plicated interlocking in control equipment and 



they insure the correct sequence of the op- 
erations. 

It is essential that these small auxiliary con- 
tacts be kept clean. They should be properly 
adjusted for right operation. Otherwise, if 
they fail, the entire controller apparatus can- 
not function correctly. 



TROUBLE 
Faulty operation 



Poor contact 



CURE 
•Adjust, or otherwise correct. 
Check opening and closing; 
necessary. 
» Dress, like other contacts. 



adjust, if 



57 



PLAN MAINTENANCE MANUAL 



Arc Boxes and Chutes 



TROUBLE 
Badly pitted or burned 
through 



Broken or damaged . 

Interference with moving parts — Adjust. 



CURE 

Replace. 

Repair or replace. 



Fuses 

Most fuse clips and ferrules are plated to contact surfaces. It is also a very important 

resist corrosion. Except where silver plated, practice to make sure that the fuses fit snugly 

remove fuses once in a while and polish the into the clips. 



TROUBLE 
Blowing too soon 



Blowing too slow. 



CURE 
Examine fuse; if too small, replace. 
Check for overloaa. 
Use plated clips and ferrules. 
Keep clips and ferrules clean. 
If contact pressure is weak, increase it. 
Install right size fuse for application. 



Rectifiers 

Little maintenance needed. Blow off excess Adjust output, if aging. If the device proves to 

dust to aid ventilation. Keep connections tight. be faulty, replace it. 



TROUBLE CURE 
Overheating, breakdown,*!— Correct overvoltage. 

or burning * Consult manufacturer for possible mis- 
application. 
Check circuit for overcurrent. 


Shorted 


Replace defective part. 



Relays 



TROUBLE 
Magnet Ty pe 
Binding, corrosion or dirt- 
Dash pot operation: 
Sticking 



Too fast or too slow 

Incorrect assembly 

Shorted turns — — — - 



Worn or broken parts 

Wrong coil 



CURE 
> Clean with carbon tetrachloride. 

• Clean and adjust. 

Change fluid, fill to proper level. 

Check with manufacturer. 
.Test coil; and replace, if necessary. 

Replace. 

Install one correctly rated. 



Thermal Type 
Failure to reset - 



Faulty tripping: 

Binding, dirt, corrosion- 
Damaged relay 

Trips at wrong 

temperature 

Heating , 



Welding or burning- 



Replace broken or Worn parts. 
Clean and adjust. 

Clean and adjust. 

Replace. 

Check rating and load; replace with 
proper coil or heater. 

Tighten loose connections. 

Clean contact surfaces. 

Check for short circuits, vibration, corro- 
sion, dirt. 



58 



INDUSTRIAL CONTROLS 



Relays (continued) 



Timing Type 

Jamming or sticking Clean and lubricate. 

Replace damaged parts, if necessary. 
Time too long: 

Weak spring and tip— Check with manufacturer's instructions, 
pressure 
Time too short: 

Dirt in gap Clean. 

Excessive spring or tip 

pressure See manufacturer's instructions. 

Misalignment Correct condition, and remedy cause. 

Worn or broken parts Clean off dirt; replace, if necessary. 



Resistors 

Provide as much ventilation as possible, tions tight. Replace units that are broken or 
and blow off dust occasionally. Keep connec- burned out. 



TROUBLE 
Open circuits - 



Overheating 



Insulation failure 



CURE 
Check connections; and locations. 
Replace worn and broken parts. 
Replace resistor. 

Check ventilation; if restricted, relocate. 
Check rating with load and operation. 
Look for loose connections. 
Check voltage of system; replace dam- 
aged parts. 
Keep clean and dry. 



Switches 

The maintenance checks and practices that to watch, especially with respect to sliding 
have been recommended for contacts are contacts, such as those in drum and knife 

also pertinent to most switches. Other points switches and rheostats, are given below. 



TROUBLE 
Drop-out failure, if magne 
operated: 



CURE 



Check instruction sheet, and adjust. 



Binding 

Improper adjustment Same as for binding. 



Worn bearings 
Insulation failure 



Overheating 



Pick-up failure 



Replace. 

Keep clean and dry. 
Correct voltage, if that is at fault. 
Replace parts, if necessary. 
Lubricate, as advised by manufacturer. 
Check for overload and poor contact. 
If service requires it, use special alloy. 
- Check for low voltage on coil. 
Replace, if coil or shorted turn is to blame. 
If coil is wrong, check with maker. 
When magnet is overloaded, or gap is 
excessive, check instruction sheet. 



Transformers 

Little maintenance required, if used within Keep connections tight. Where required, keep 
rated capacity. Do not overload continuously. oil in cases. Inspect oil periodically. 



TROUBLE 

Insulation failure 



Open circuits 
Overheating - 



CURE 
.Check system voltage; replace damaged 

parts. 
Keep clean and dry. 
Check and tighten connections. 
Rewind; or replace. 

Observe load and system voltage, and 
frequency of operation. 



59 



PLANT MAINTENANCE MANUAL 



Wiring and Connections 

Connections are usually bolted, clamped or Do not overload wiring. See that connections 
soldered. Make sure that wires of proper ca- are tight. Also be sure to keep them clean 
pacity are used and that they are insulated. and neat at all times. 



TROUBLE 
Grounds, short circuits 

Insulation defects 

Looseness 



Overheating and open 
circuits 



CURE 
• Look for defective wiring; replace. 
.Repair; or replace. 
•Tighten. 

Check for loose connections. 




60 




CHAPTER 7 



SWITCHING EQUIPMENT 



This chapter will treat of industrial plant 
apparatus rather than large utility company 
equipment. Standard practices of the National 
Electrical Manufacturers Association (NEMA) 
have been followed. Safety provisions of the 
new National Electrical Code should be ob- 
served in all applications. 

Manufacturers prepare elaborate instruction 
books covering the installation, operation and 
maintenance of switchgear products. These 
instructions are most specific and helpful, so 
be sure to follow them at all times. 

A switchboard is defined as "a large single 
panel, frame, or assembly of panels, on which 
are mounted, on the face or back or both, 
switches, overcurrent and other protective de- 
vices, buses, and usually instruments. Switch- 
boards are generally accessible from the rear 
as well as from the front and are not intended 
to be installed in cabinets." They are primarily 
main secondary centers which control large 
amounts of energy through a few branch 
feeder circuits to distribution panelboards, to 
lighting or power mains or panelboards, or 
to buses and the like. 

Modern developments for industrial appli- 
cations are the dead-front boards and the 
totally enclosed types of equipment. These 
safety forms of apparatus offer such advan- 
tages as full protection to operators; ade- 
quate housing of equipment from dust and 



dirt; compact minimum space requirements,- 
easy installation and simple, low-cost main- 
tenance since the breakers and other pieces 
of switching apparatus are easily removed 
for inspection. 

The National Electrical Code (NEC) speci- 
fies that switchboards which have any live 
parts should be located in permanently dry 
locations. They should be under competent 
supervision and be accessible only to quali- 
fied persons. If located outdoors or in a wet 
location they should be housed in a weather- 
proof enclosure. 

If any electrical equipment has been added 
to a plant, have the switchboard checked for 
adequate interrupting capacity by a compe- 
tent manufacturer or utility company. 

The safety features of metal-clad switch- 
gear are important factors in these modern 
types of complete, factory-assembled, metal- 
enclosed units. Other advantages have al- 
ready been mentioned. 

Panelboards 

A panelboard is defined as "a single panel 
or a group of panel units, designed for assem- 
bly in the form of a single panel; including 
buses, and with or without switches and/or 
automatic overcurrent protective devices for 
the control of light, heat and power circuits 
of small individual as well as aggregate ca- 



61 



PLANT MAINTENANCE MANUAL 



pacify; designed to be placed in a cabinet or 
cutout box placed in or against a wall or 
partition and accessible only from the front." 
Four general applications of panel boards 
are lighting and appliance branch circuit 
panelboards, lighting distribution panelboards, 
power panelboards and power distribution 
panelboards. 

Proper Installation Is Important 

Proper design and manufacture and proper 
installation, operation and care are essential 
to the successful operation of switchboards 
and panelboards. Serious trouble can arise 
if certain fundamental requirements are not 
observed. These points are much the same re- 
gardless of the kind of board. 

Wherever possible panelboards and cabi- 
nets should be located where suitable atmos- 
pheric conditions prevail. The location should 
be clean, dry and non-corrosive. The normal 
ambient temperature should not exceed TOO 
deg. F. 

If atmospheric conditions are damp and 
moist, the weatherproof type of equipment 
should be used. If the location is dusty or ex- 
posed to flying particles, dust-tight construc- 
tion is important. Where conditions are very 
unusual, special features of construction are 
essential. 

Since high ambient temperature wili cause 
cables and panelboard parts to heat exces- 
sively, it is most important not to install boards 
where the mounting surface or the surround- 
ing air is high in temperature. Where high 
temperatures cannot be avoided, common 
practice is to derate the panelboard by using 
current carrying parts, over-current devices, 
wires and cables with "double the actual 
capacity of the branch circuit and main bus- 
bar loads." 

The cabinet should be fastened securely to 
a plane, even surface so that the back is true 
and plumb. After installing the conduits, be 
sure to see that all unused conduit openings 
are closed in order to keep dust and moisture 
out of the cabinet. After the wires have been 
pulled, but before installing the panelboard 
interior, inspect the cabinet for scratches in 
the corrosion protection finish. Damages to 
the finish should be protected with paint or 
other coating. 

Keep Panelboard Interiors Clean 

Store panelboard interiors in a place that 
is clean, dry and normal in temperature while 
awaiting installation. In unpacking, use care 
so as not to damage the panelboard. Inspect 



it carefully, noting that all connection and 
mounting screws are tight. 

Install the interior and secure it in the cabi- 
net as required by the mounting and adjusting 
means provided. When connecting up the 
wires, make sure that they are secured tightly 
in the terminals,- then arrange the wires neatly 
in the gutters. Since these wires generate 
heat within the enclosure, it is well to remem- 
ber that too much wiring is an unnecessary 
cause of heating troubles. 

After all connections have been made, clean 
out cut ends of wire and other foreign sub- 
stances. Then install the door and trim. 

Use care in unpacking the panelboard front, 
and check it also for damage to the paint or 
other protective finish. Touch up with suitable 
coating where corrosive protective finish has 
been damaged. 

Align and level the front with the building, 
even to the extent that the cabinet may be 
"out of true." Proper alignment and adjust- 
ment of the cabinet front with the building 
and the panelboard interior are necessary 
before securing the front in place. 

The directories or cardholders which are 
supplied with the boards should be filled out, 
designating the location of the loads con- 
trolled by the various circuits. 

Check and test all wiring for grounds, short 
circuits, etc., before supplying power to the 
panelboard. 

CARE AND MAINTENANCE 

Period inspections are essential to the proper 
maintenance of panelboards since the satis- 
factory and successful operation of the board 
is in direct relation to the amount of care 
and maintenance it receives. 




Modern Panelboard 



62 



SWITCHING EQUIPMENT 





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c0rl 








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3 






Modern Switch gear 







In examining them regularly from time to 
time, make sure that the boards and panels 
are clean and free from dirt and moisture. 

Check also the connections between unit 
parts and the busbars and those between the 
units and the wires. Tighten them whenever 
necessary. 

Other items to be examined are the fuse 
contacts. If of the plug type, they should be 
inspected and tightened frequently. Fuses and 
connections tend to loosen from the repeated 
expansion and contraction caused by the 
alternate heating and cooling of the panel- 
boards as the current is turned on and off. 
Insure good contact and avoid heating and 
other troubles by maintaining tight connections. 

Operating Temperatures 

Panelboards should be inspected under load 
periodically to determine if excessive oper- 
ating temperatures are present. Because of 
the resistance of the various parts, current- 
carrying panelboards generate heat higher 
than that of the surrounding area. When 
boards are evenly loaded, the top part 
usually has the highest temperature. 

The cumulative heating effect of grouping 
these heat-generating parts in an enclosure 
causes the individual parts to heat more than 
if operated alone. 

Since copper parts tend to oxidize rapidly 
at temperatures above 176 deg F, or 80 deg 
C, the maximum temperature should not ex- 
ceed this value. 



This cumulative heating, which develops be- 
cause of the grouping of the devices within 
panelboard enclosures of the thermal circuit 
breaker and fused types, tends to cause indi- 
vidual breakers to trip and fuses blow at less 
than rated current loads. These over-current 
protective devices thus protect wire and cable 
insulation against excessive operating temper- 
atures. 

Detecting Temperature Troubles 

The maintenance of low operating temper- 
atures is necessary to satisfactory perform- 
ance and long and trouble-free life. 

Symptoms of excess operating temperatures 
are as follows: 

a. Discoloration of copper conducting parts. 

b. Melting of sealing wax used to insulate 

or seal holding screws. 

c' Deterioration of insulating materials. 

The best detector of excessive temperatures 
is, of course, a thermometer or thermo-couple. 
Because of the fact that heat flows from the 
higher to the lower temperatures, the direc- 
tion of heat flow can be established by ascer- 
taining the point of highest temperature. Thus 
the necessary corrective measures can be 
applied. 

In panelboards that employ a large number 
of fuses, as much as 80% of the heat gener- 
ated in the enclosure may come from the 
fuses. Some kinds of fuses, however, generate 
less heat than others. 

Whether the source of heat is a circuit 



63 



PLANT MAINTENANCE MANUAL 



breaker or a fuse, the ratio of the panel cir- 
cuit loads should never exceed 70% of the 
rating of the device. The ratio is essential to 
satisfactory performance where loads are 
continuous for three hours or more. In case of 
intermittent duty loads, this ratio is highly 
desirable. 

Circuit Grounds 

Overloads which are not heavy enough to 
open over-current protective devices are often 
added to panelboard circuits from grounds in 
the circuit. Because of their small magnitude 
they are hard to detect. Nevertheless since 
they increase operating temperatures, they 
should be investigated. The inspection made 
for determining excessive temperatures is also 
a good one for detecting these grounds in 
the system. 

Condensation 

Condensation in conduits should be guarded 
against because it may cause moisture to drop 
on busbars or other parts that conduct cur- 
rent and create leakage currents or arc flash- 
overs. This condition may be found particularly 
where the conduit enters at the top of the 
cabinet. Condensation moisture may be kept 
off electrical parts by inserting a baffle of in- 
sulating material between the conduits and 
the panelboard proper. 

Lubrication 

To provide smooth operation and to pre- 
vent excessive wear, it is necessary to oil the 
operating- parts of the panelboard — but not 
the circuit breakers. Avoid using too much 
oil. A drop or two of clean, good-grade, 
light, sludge-free oil will lubricate the sliding 
contacts. 

CIRCUIT BREAKERS 

A circuit breaker is "a device designed to 
open under abnormal conditions a current- 
carrying circuit without injury to itself." It 
may be opened either manually or automati- 
cally, but when operated manually only, it 
is merely a switch. Most circuit breakers, how- 
ever, are controlled manually as well as auto- 
matically — manually with a hand lever and 
automatically with solenoids or other electrical 
means or pneumatic mechanisms. 

Circuit breakers are classed according to 
whether the contacts open in air or under oil. 

The most frequent method of tripping cir- 
cuit breakers is on overcurrent, and the action 
may be either instantaneous or after a certain 
interval of time. Tripping, however, may also 
occur from undervoltage. 

On small industrial breakers, tripping action 



is usually obtained with trip coils which are 
within the breaker. The latching mechanism 
of the breaker is released by the action of 
the trip coil on the trigger. 

In oil circuit breakers, automatic tripping 
may be accomplished through either poten- 
tial or current trip coils in combination with 
protective relays. 

Even though circuit breakers may not be 
put in serv'rce for some time, it is advisable 
to set them up immediately in their proper 
positions. If circuit breakers have to be stored, 
be sure to keep them in clean, dry places, not 
exposed to dirt, corrosive gases or mechani- 
cal injury. Take care not to subject the appa- 
ratus to shocks and jars from rough handling. 

AIR CIRCUIT BREAKERS 

Air circuit breakers have been used princi- 
pally in low voltage systems - usually up to 
600 volts a-c, 250 volts d-c for protective 
services. Recently, however, their use with 
special interrupting devices has been ex- 
tended to 15 kv. They will be found on high 
voltage plant distribution circuits and on trans- 
former primaries. 

Modern circuit breakers require relatively 
little replacement of parts. They should, how- 
ever, receive periodic and systematic inspec- 
tion, especially of contacts and mechanisms. 
Proper installation is essential to good oper- 
ation and low-cost maintenance. Follow man- 
ufacturers' instructions carefully in this, and 
all, respects. Recommended inspections after 
installation include the following: 
Check for proper and level set-up on the sup- 
porting structure. 
Make sure bearing surfaces of operating 
mechanisms have been lubricated, if re- 
quired. 




64 



SWITCHING EQUIPMENT 



WHAT TO CHECK WHAT TO LOOK FOR 


Coble 
Connections 


Overheating of terminal connectors. 
Condition of all joints. 


Contacts 


Amount of closing and opening "wipe." 
Cleanliness and freedom from dirt and dust. 
Pitting or burning of arcing contacts. 


Control and 

Auxiliary 

Switches 


Proper functioning. 


Enclosed 
Devices 


Condition of enclosure and ground con- 
nection. 
Working order of handle. 


Interrupting 
Devices 


Excessive erosion, burning or breakage. 


Mechanisms 


Security of nuts, bolts, pins or cotter pins. 
Working order of rods and moving parts. 
Functioning of all parts. 
Lubrication at bearing points. 


Tripping 
Devices 


Freedom of movement. 
Calibration setting. 

Oil and oil cup, if equipped with oil-film 
timers or oil-dashpot devices. 


Undervoltage 
Devices 


Positive tripping. 

Cleanliness of oil pot, if of dashpot type. 



Close breakers slowly to check adjustment 
and alignment of contacts and other oper- 
ating parts. 

Examine contacts for good pressure when 
closed. 

Test wiring for damage during installation and 
for grounds or short circuits. 



Inspections For Air Circuit Breakers 

Local conditions determine the frequency of 
inspection. In general, however, complete in- 
spections should be made at least once a year 
—also after a severe short circuit. 

A suggested inspection check list is pre- 
sented. 




MODERN SWfJCHGBAR 



65 



PLANT MAINTENANCE MANUAL 



AIR BREAKER TROUBLES — CAUSES AND CURES 


IF BREAKER 


WHAT TO CHECK 


WHAT TO DO 


Overheats 


Contacts: 

Improper meeting. 


Adjust. 


Dirt or grease. 


Clean. 


Pitting or burning. 


Dress and fit. 


Inadequate connec- 
tor bar or cables. 


Replace. 


Loose connections. 


Tighten. 


Overcurrent. 


Rearrange circuits, 
or replace with 
adequate 
breaker. 


High ambient tem- 
perature. 


Provide means of 
cooling, or relo- 
cate in cool place. 


Wont 
Trip 


Pin worn or dam- 
aged, 


Replace. 


Insufficient move- 
ment for release 
of tripping latch. 


Correct adjustment. 


Dirt clogging over- 
load device arma- 
ture. 


Clean thoroughly. 


High calibration. 


Set for correct load. 


Control line: Blown 
fuse. 


Replace. 



Check also the load current, voltage and 
heating conditions of the circuit breakers. The 
load current should not exceed the ampere 
rating of the breaker. Watch also for over- 
heating of current-carrying parts. The oper- 




ating voltage of electrically operated break- 
ers should be sufficient for proper operation. 
Watch for overheating of breakers when they 
are carrying full-load current. 

Open and close electrically operated break- 
ers a few times by hand; if satisfactory, then 
operate the breaker electrically several times. 

OIL CIRCUIT BREAKERS 

In oil circuit breakers, the breaker contacts 
open under oil; the cooling effect and the 
pressure of the oil help to extinguish the arc. 
They are used for voltages above 600. 

Be sure to follow manufacturers' instructions 
for installing and mounting the equipment be- 
cause proper installation is necessary to suc- 
cessful operation and to low-cost mainte- 
nance. 

Suggested inspections to follow complete 
installation are as follows: 
Check for proper set-up and level on sup- 
porting structure. 
Observe bearing surfaces of operating mech- 
anisms for proper lubrication. 



66 



SWITCHING EQUIPMENT 



AIR BREAKER TROUBLES — CAUSES AND CURES 


IF BREAKER 


WHAT TO CHECK 


WHAT TO DO 


Won't 
Trip 


Broken wire or faul- 
ty connection. 


Repair. 


Burned or damaged 
control switch. 


Repair damaged 
parts. 


Dirty, sl.udged or 
gummed oil in oil- • 
film timer. 


Clean oil pot, and 
fill with clean oil. 


Trips 

Too 

Often 


Calibration too low. 


Reset for proper 
load. 


Latch worn. 


Replace. 


Poor contact of aux- 
iliary contacts. 


Clean, adjust or re- 
new, as required. 


Faulty oil film timer. 


Clean oil pot and , 
fill with clean oil. 


Won't 
Close 
or 
Latch 


Out of adjustment. 


Readjust or replace, 
as necessary. 


Fault in control 
source, switch or 
relay: Blown fuse. 


• 
Replace. 


Damaged con- 
tacts. 


Replace. 


Control wiring. 


Repair fault 


Voltage drop in 
leads. 


If too much, install 
larger wire. 


Control voltage too 
high or too low. 


See that voltage is 
within limits specified 
by manufacturer. 



Close breaker slowly by hand to check 
adjustment and alignment of contacts and 
other operating parts. 

Make sure that tanks are filed with sufficient 
oil. 

See that joints have been correctly made. 

Examine wiring for damage during installa- 
tion, and test for grounds or short circuits. 

Note current-carrying parts for proper insula- 
tion where necessary. 

Inspections 

Frequency of inspection depends upon sur- 
rounding circumstances, and it can be best 
determined by a company's experience under 
actual operations. Standard practice never- 



theless calls for a complete and thorough in- 
spection at least once a year. The oil, how- 
ever, should be inspected and tested at least 
twice a year, or every few months, and after 
heavy fault interruptions. 

Oil which is contaminated with dirt or mois- 
ture or by oxidation should be filtered and 
retested for dielectric strength before reuse. 
The dielectric strength of new oil should be 
at least 22 kv, and when the oil strength 
drops to 16.5 kv or less, it should be filtered. 
Examine the oil storage reservoir and con- 
necting piping periodically and keep them free 
from moisture. 

Check the oil-level gage and maintain oil 
in the tanks at the right level. 



SAFETY ALWAYS 
Before inspecting or repairing, make sure 
that the breaker and all mechanisms are dis- 
connected from all electric power. 



67 



PLANT MAINTENANCE MANUAL 



OIL BREAKER TROUBLES — CAUSES AND CURES 



IF BREAKER 



Overheats 



WHAT TO CHECK 



Contacts— alignment 
and adjustment. 



Burning and pitting. 
Current overloading. 



Cable or connection 
bars. 



Loose connections. 



High ambient 
perature. 



tern- 



WHAT TO DO 



Line up and adjust. 



Dress up or replace. 



Rearrange circuits or 
replace with ade- 
quate breaker. 



Increase capacity or 
remove excess 
current. 



Tighten. 



Provide cooling ar- 
rangement, or re- 
locate in cool lo- 
cation. 



Won't 
Trip 



Mechanism binding 
or sticking. 



Lubricate, or adjust 
mechanical de- 
vices. 



Latching device fail- 
ure. 



Damage to trip 
coil. 



Replace, if worn or 
corroded; or ad- 
just wipe. 



Replace coil. 



Blown fuse. 



Replace. 



Contacts, dirty or 
damaged. 



Clean, dress or re- 
place. 



Faulty connections. 



Tighten or repair. 

Lubricate, or adjust 

mechanical de- 

£i££L 



Wont 
Close or 
Latch 



Mechanism sticking 
or binding. 



Closing coil, 



Replace, if burned 
out. 



Closing relay stick 
ing. 



Adjust. 



Cut-off switch: opens 
too soon, or too 
late. 



Voltage drop in 
leads. 



Adjust accordingly. 



Improve contacts or 
install larger 



wires. 



Faulty connection, 
broken wire, 
blown fuse in 
control circuit. 



Repair or replace. 



Insufficient 
Oil 



Leakage. 



Check and repair 
leak. 



Contaminated 
Oil 



Carbonization, mois- 
ture or sludge. 



Drain and filter, or 
^use^jewoil^^^ 



Insulation 
Fails 



Moisture, dirt, car- 
bon on insulating 
parts. 



Clean thoroughly. 



68 



SWITCHING EQUIPMENT 



1 WHAT TO CHECK WHAT TO LOOK FOR | 


Contacts 


Proper alignment and adjustment. 
Firm, even bearing pressure. 
Roughness, pitting, burning. 


Connections 


Overheating. 
Cleanliness and security. 


Bolts. 
Nuts, Pins 


Condition and tightness. 


Mechanisms 


Freedom and smoothness of move- 
ment. 
Bearing point lubrication. 
Cleanliness. 
Adjustment of breaker stroke. 


Bushings 
or Insulators 


Cleanliness of surfaces. 
Dielectric. 

Condition and alignment, firmness of 
support. 


Auxiliary 
Switches 


Condition and adjustment. 


Interlocks 


Proper functioning and adjustment. 


Undervoltage 
Devices 


Positive tripping action, or time let- 
ting. 


Valves and 
Fittings 


Oil leakage. 
Entrance of water. 


Tanks and 
Housing 


Damaged surface. 
Oil leakage. 


Such checks as dielectric loss measurements of 
bushings, speed and timing tests on circuit breakers, 
proper functioning of dashpots, grounding of bushing 
flanges, breaker tanks and breaker frames are also 
important. 



Other parts to inspect and what to look 
for are given in the accompanying check list. 

Electrical Checks 

Electrical — The operating voltage should be 
checked to see that the full operating current 
is sufficient. See that the closing relays func- 
tion properly and if any indicating lamps have 
burned out. Make sure that the tripping action 
is positive. Opening and closing time at nor- 
mal control voltage should also be checked. 

RELAYS 

According to NEMA Standards a relay is 
"a device that is operative by a variation in 
the conditions of one electric circuit to effect 
the operation of other devices in the same or 
another electric circuit". 

Since it is the function of a protective relay 
to do what its name implies, one that is out 
of order, then, is of no value at all. Relays 
must be in good working order at all times 



and proper maintenance is essential to their 
well-being. 

Relays should be examined carefully at 
least once a year, and those of the precision 




69 



PLANT MAINTENANCE MANUAL 



or high-speed types should be operation-tested 
at least twice a year. The same periodic in- 
spection applies to oil dashpots, leather bel- 
lows and other similar devices on relays that 
are so equipped. Tests should also be made 
at any time that their accuracy or the adjust- 
ments are in doubt. 

Many modern relays now have removable 
elements which are an aid to maintenance 
and safety. 

Do not use emery or crocus cloth on silver 
relay contacts. 

Always follow manufacturers' instructions on 
the operation and maintenance of their relays 
and employ only skilled technicians in any 
work to be done on the equipment. 



SWITCHES 

The standard definition of the NEMA for 
a switch is "a device for making, breaking, or 
changing the connections in an electric cir- 
cuit". 

Enclosed switches with external operating 
handles or levers are used extensively in in- 
dustry. Disconnecting switches are employed 
for disconnecting circuit breakers and the 
like for inspection and repair, and are not 
to be used to open or close a circuit when 
the load is on the line. The circuit must be 
open at some other point in the line when a 
disconnect switch, which is usually used on 
high-voltage circuits, is opened or closed. 

Examine all switches periodically and gen- 



INSPECTION CHECK LIST FOR RELAYS 


WHAT TO CHECK 


WHAT TO LOOK FOR 


General 
Condition 


Dirt, dust, loose or broken parts, 
and wires. 


Contacts 


Alignment. 

Freedom of operation. 

Dirt. 

Pitting, roughness, tarnishing. 


Moving Parts 


Freedom of movement. 
Dirt or dust. 


Operation 


Noisiness. 

Loose parts, screws, nuts, etc. 


Connections 


Looseness. 


Insulation 


Deterioration or other damage. 


Timing Features 


Settings. 

Bellows, if any. 

Oil film or dashpot, if used. 



TROUBLE CHECK LIST FOR RELAYS 


SYMPTOM 


WHAT TO CHECK 


Faulty 
Operation 


Calibration settina for protective re- 
quirements. 

Contacts — for proper contact and 
adjustment, dirtiness, burning, pit- 
ting, tarnishing, corrosion. 


Failure 

to Trip Breaker 


Setting for circuit conditions. 

Open or short circuits. 

Faulty timing device. 

Target and holding coil application. 


Sluggish 
Movement of 
Parts 


Dirt, dust or dried oil accumulations. 


Dust or dirt in mechanism. 
Sufficiency of current. 
Linkage binding. 
Armature setting. 


Target Not 
Indicating 



70 



SWITCHING EQUIPMENT 



eral inspections should be made at least 
once a year. Because of their availability or 
repeated use, the condition of some switches 
can be noted frequently, but where switches 
are infrequently seen or used or are in iso- 
lated locations they should by no means be 
neglected. 

When switches are inspected extreme cau- 
tion should be exercised at all times to avoid 
making contact with live parts. Especially 
should this precaution be observed where 
switches have ratings of 600 volts and over. 
Make sure, therefore, that all parts are elec- 
trically dead. 

Switch Troubles 

Some causes and cures for the overheating 
of switches are shown in the accompanying 
table. 



FUSES 

A fuse is "an overcurrent protective device 
with a circuit-opening fusible member directly 
heated and destroyed by the passage of over- 
current through it." It consists of an enclosure 
made of porcelain, glass or hard fibre and a 
fusible element which melts and breaks the 
circuit when the current exceeds the rating 
of the fuse. 

Fuses are commonly installed on circuits 
"up to 600 volts and not exceeding 600 am- 
peres." Where the current exceeds these val- 
ues, high-voltage fuses, or more commonly 
oil or air circuit breakers, are used. Fuses are 
classed, therefore, according to whether they 
are used on circuits up to the figures given 
or on circuits that exceeds those values. 

In the low-voltage group of fuses there are 



CAUSE CURE 


Overload 


Re-arrange circuits for less loads, or re- 
place with more adequate switch. 


Poor 
Contacts 


Adjust. 


Inadequate 
Connections 


Replace with heavier conductor, or add 
new conductors. 


Burned or 
Pitted Contacts 


Dress and fit. 


Loose nuts 
and bolts 


Tighten. 


High 
Ambient 


Arrange cooling, or relocate in cooler 
spot. 



SWITCH INSPECTION PROCEDURES 

Wipe clean of dirt accumulations periodically. 

Open and close several times. 

Check blade contact with feeler gage. 

Clean contacts if necessary. 

Check contact or pressure and tension of 
clips. 

See that current does not exceed switch rating. 
If switches are of enclosed type, inspect 

additionally as follows: 

See that enclosures are unimpaired. 

Check working condition of handle and mech- 
anisms. 

Examine cover and interlock. 

Check ground connections. 

Keep enclosures clear for easy accessibility 
of all parts. 
In the case of disconnect switches, see that 

insulators are clean and check blade latches 

for proper functioning. 



the plug and the cartridge kinds. High-voltage 
fuses, which are contained in tubes, may be 
of several types: oil immersed, liquid filled, 
expulsion or granular filled. 

Make sure that the contacts of fuses are 
kept clean and bright. Inspect fuses periodi- 
cally to determine the condition of the con- 
tacts. Where necessary, protect the clips and 
ferrules with a coating of non-corrosive lu- 
bricant. 

Keep a check on the condition of the fuse 
tubes also. If the finish has deteriorated, clean 
and re-coat with insulating varnish. 

Other Switchgear Equipment 

Additional items of switching equipment are 
meters, interlocks, instrument transformers, in- 
dicating lamps, busbars and connections, and 
bushing current transformers, potential de- 
vices and other auxiliaries. Inspect them at 
least once a year. 



71 



PLANT MAINTENANCE MANUAL 



Meters and instruments should be inspected 
for condition and for proper registering. If 
cases are damaged or glass broken or 
cracked, the required repairs should be made. 
Meters, of course, should be tested from time 
to time, and calibrated, if necessary. 

If meters fail to register, check for blown 
fuses, broken wires and other connection 
faults. Keep meters free from dirt accumula- 
tions and from metal particles on the mag- 
nets. Repair or replace damaged and faulty 
parts. Permit only skilled technicians to work 
on meters since they are precision instruments. 

Examine instrument transformers for proper 
condition and to see that connections and 
grounding are not impaired. 

Interlocks, which are small auxiliary con- 
tacts that govern succeeding operations and 
are actuated by the operation of these other 
devices, also require inspection and check- 
ing. They should be kept clean and in proper 
adjustment. Check the opening and closing 
and adjust if necessary to correct faulty oper- 
ation. 

Inspect safety shutters for correct position 
and operation. 

Check indicating lamps periodically and 
replace those that are faulty or that have 
burned out. In making the examination see 



that the lamps give the proper "open" and 
"closed" indications. 

Observe the. condition and operation of the 
position changing mechanisms of metal-clad 
switchgear. 

Bus and Connection Bars 

Inspect busbars and connections for proper 
conditions, especially for overheating, the 
cause for which should be determined. 

If loose or poor connections are the cause 
of overheating, the condition may be cor- 
rected by transferring some of the load to 
other feeders or by increasing the carrying 
capacity of the bars. This cure is also suitable 
where overheating arises from the fact that 
additional loads have been applied subse- 
quent to initial installation of equipment. 

Overheating may also be caused by loose 
bolts and nuts in bolted joints. Inspect, there- 
fore, for such conditions and tighten fasteners 
where necessary. If the overheating has been 
serious it may be advisable to remove the 
fastenings from the mounting and clean them 
thoroughly, and grease them where desirable 
with lubricant recommended by the maker. 

Loose connections may also cause noisiness 
because of vibration. The same is true of loose 
laminations in the cores of transformers. 



r 

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72 




CHAPTER 8 



LEATHER BELTS 



Present day leather belts are cut from the 
middle portion of the hide, at or near the 
backbone. This section of the hide, called the 
belting "bend", leaves the neck, legs and tail 
sections unused for belting purposes. Contrary 
to the old method of often cutting strips across 
the hide, at right angles to the backbone, the 
present method is to cut strips parallel to the 
backbone. First quality leather belting is cut 
from a small section of the hide, comprising 
about 25% of the entire hide area. 

Hides are first cleaned of fat and flesh and 
cured with salt. After curing, washing and re- 
moval of hair, the hides are tanned by being 
progressively immersed in "tan liquors". These 
solutions may contain extracts of various veg- 
etable tanning materials, such as oak bark, 
chestnut wood, quebracho, etc., and leather 
so tanned is said to be "vegetable tanned" 
or "oak tanned". If the tanning solution con- 
tains mineral salts, such as chromic acid, the 
leather is said to be "mineral tanned" or 
"chrome tanned". 

For the purpose of blending the qualities of 
leather created by tanning, many combination 
tannages are used. Usually oak tanned leather 
is firmer than chrome tanned leather, but does 
not have as good friction, nor is it as resistant 
to water as the chrome treated leather. The 
two tannage qualities are often combined by 
having a ply of chrome tanned leather ce- 
mented to an oak tanned ply. 



BELT CONSTRUCTION 

A cattle hide is not uniform in strength and 
thickness. The thickness may vary j 1 ^ of an 
inch from one part of the hide to another. 
Because of this, great care is necessary in cut- 
ting and matching the leather strips to make 
a "balanced" belt. 

A properly made single ply belt will lie 
curved on the floor or bench but will run 
straight on the pulleys. A double or triple ply 
belt can be "balanced" against lateral curva- 
ture by cementing strips together which tend 
to curve in opposite directions. Thus a double 
or triple belt, properly made, relaxed or under 
tension, is straight to the eye under all con- 
ditions. 

Not only does the strength of the leather 
vary from one part of the hide surface to an- 
other but also the strength of the leather is 
greater on the flesh side than on the hair or 
"grain" side. 

The grain side, however, presents a better 
friction surface than does the flesh side, so it 
is consequently run against the pulleys. When 
a double belt is made, the flesh sides are ce- 
mented together exposing a grain surface on 
both sides of the belt. When using single belts 
the English practice is to run the flesh side to 
the pulley, since that is the* way the leather 
bends naturally on the animal. 

The hide of any animal is porous and is 
maintained in a soft pliable condition during 



73 



PLANT MAINTENANCE MANUAL 



■<■*< 



<.': s '*;i '■:.'*' 



%-'i\ 






NECK 




Portion of hide from which leather belting is cut. 



74 



LEATHER BELTS 



the life of the animal by the secretion ot oils 
from Ms body. After the hide is removed, how- 
ever, it will eventually dry out in the atmos- 
phere, becoming stiff and hard and having a 
lower coefficient of friction. The oils lost in 
the processes of leather manufacture are re- 
stored to it in that part of the currying process 
known as "stuffing" Unless the leather belt is 
occasionally lubricated by a suitable belt dress- 
ing during its use, its life will be shortened 
and its capacity, because of internal friction 
and of hardening and cracking of the pulley 
side of the belt, shortened. 

Thus it can be seen that a belt dressing 
does two distinct things to a leather belt: first, 
it lubricates the internal fibers, thereby re- 
ducing friction due to bending or flexing of 
the belt, and; second, it tends to maintain the 
coefficient of friction on the pulley side of the 
belt by keeping it in a soft, pliable condition. 

Such substances as beef tallow, stearine, 
fish oils and some vegetable waxes are used 
as belt dressings. Mineral oils and waxes will 
not lubricate a belt or preserve its friction 
surface. Rosins will temporarily improve the 
coefficient of friction of a belt but they will 
ultimately glaze and destroy the surface not 
only of leather but also of rubber, balata and 
bare fabric belts as well. In all cases, only 
belt dressings recommended by the maker 
should be used. 



Being a hide and not a woven or twisted 
material, leather does not easily become 
frayed or raveled by wear in the course of 
flexing over pulleys, rubbing against pulley 
flanges, belt guides or shifters, or by the con- 
centrated stresses set up by belt hooks, laces, 
plates, bolts and rivets. Having no warp or 
woof it is a most satisfactory material for 
taking and maintaining belt fasteners, espe- 
cially of the rawhide, the tanned leather or 
wire lace types. 

The most satisfactory belt is an endless belt. 
Practical convenience and the frequent neces- 
sity of fastening a belt on many drives re- 
quire that joints be readily made. Leather is 
one of the belt materials that can be made 
endless on the job with relative ease. A belt 
made up of this material may be used again 
and again on one drive or another by length- 
ening, shortening or narrowing. If a leather 
belt is installed on the drive too tightly it will 
stretch out, thereby reducing the excessive 
tension without injury to itself. 

The coefficient of friction of leather im- 
proves with proper use. Due largely to the 
fact that its coefficient of friction increases 
with slip a leather belt has a high overload 
capacity. By selection of tannage and water- 
proofing, leather can be made adaptable to 
almost every drive condition and, when pro- 
perly used, generally has a long life. 




MAGNIFIED SECTION 
OF SINGLE PLY CUT IN 
THREE EQUAL PARTS 



75 



PLANT MAINTENANCE MANUAL 



Belt Size 

Select proper size belt for the load to be 
transmitted using the Horse Power Rating 
Tables for Oak Tanned Flat leather Belting 
approved by the American Leather Belting As- 



ENGINEERING 

sociation and which are given in Tables I, II 
and III in this chapter. To find the width of 
belt required, using these tables, divide the 
nominal horse power load to be transmitted 
by the factors selected from Tables I, II, and III. 




Pulley Size 

Use proper size pulleys to obtain desired 
machine speed. The most economical belt 
speeds lie between 1500 and 4500 feet per 



minute. Belt speed can be computed from the 
formula given elsewhere. The diameter of pul- 
leys should be kept as large as practical so 
as to minimize the flexing strain on the belt. 




Short Center Drives 

On all electric motor drives with short dis- 
tances between pulley centers it is advisable 



to use a pivoted type motor base. For short 
center drives on fixed centers, investigate 
flexible idler drives. 




Design 

Wherever possible, belt drives should be so 
designed to have the tight side of the belt on 



the bottom. Such an arrangement makes it 
possible to provide maximum arc of contact 
with the pulleys. 




76 



LEATHER BELTS 



TO ORDER LEATHER BELTS - 

When ordering leather belts, user should furnish belt supplier with: 

/Belt requirements as to: 
(a) type 

(b) width 

(c) thickness 



Whether belt is to be sup- 
plied: 

(a) made endless at the fac- 
tory 

(b) laps prepared for cement- 
ing on the job 

(c) ends cut square for lacing 



The smallest steel tape length 
around pulleys. (Be sure to 
state that it is steel tape mea- 
surement and manufacturer 
will make proper deductions 
for initial stretch.) 




Belt* 
Under 

8" Wide 


SINGLE PLY 


DOUBLE PLY 


TRIPLE PLY 


11/44" 13/44" 


U/44" 10/44" 13/44" 


30/44" 34/44" 


Med. Heavy 


Light Med. Heavy 


Med. Heavy 


3" 5" 


4" 8" 12" 


20" 24" 


Belts 8" 
and 
Over 
Wide 




8" 10" 14" 


24" 30" 


These are the minimum allowable pulleys for the 
above thickness belts. 



PULLEY 
DIAMETER 



The driven pulley 
from formula: 



diameter can be calculated 



d = 



DXN, 



Belt speed can be computed from the formula: 

S = D X N X 0.262 
where S = Belt speed in feet per minute. 

D = Diameter of pulley in inches. 

N = Pulley speed in RPM. 
For open drive i \\ _ a\* 

L = 2C + 1.57 (D + d) +- 



BELT 
LENGTH 



For crossed drive 

L = 2C + 1.57 (D + d) 



4C 

(D + d)' 



4C 



where L = Length of belt in feet. 

C = Pulley center distance in feet. 
D = Diameter of large pulley in feet, 
d = Diameter of smaller pulley in feet, 
n = The driven pulley speed in RPM. 
N = The driver pulley speed in RPM. 



77 



PLANT MAINTENANCE MANUAL 



H. P. POWER RATINGS FOR OAK TANNED FLAT LEATHER BELTING 

American Leather Belting Association 
Directions for Use: 

To find width of belt required: Divide name plate reading of prime mover 
or nominal load by values in Table I, Table II, Table III. To find rating 
of a belt: Multiply belt width by values in Table I, Table II, Table III. 

TABLE I 
Horse Power per Inch of Width 



Belt Speed 

Feet per 

Min. 



I »! 

e « « 

ilJ 

3 a 



Belts 

Under 8" 

Wide 

Belts 8" 

and Over 

Wide 



SINC 


HE PLY 


DOUBLE PLY 


TRIPLE PLY 


11/ " 
/64 


13/" 
/64 


18/ " 20/ " 23/ " 
/64 ^4 /64 


30/ " 34/ " 
/64 /64 


Med. 


Heavy 


Light Med. Heavy 


Med. Heavy 



600 


1.1 


1.2 


1.5 


1.8 


2.2 


2.5 


2.8 


800 


1.4 


1.7 


2.0 


2.4 


2.9 


3.3 


3.6 


1000 


1.8 


2.1 


2.6 


3.1 


3.6 


4.1 


4.5 


1200 


2.1 


2.5 


3.1 


3.7 


4.3 


4.9 


5.4 


1400 


2.5 


2.9 


3.5 


4.3 


4.9 


5.7 


6.3 


1600 


2.8 


3.3 


4.0 


4.9 


5.6 


6.5 


7.1 


1800 


3.2 


3.7 


4.5 


5.4 


6.2 


7.3 


8.0 


2000 


3.5 


4.1 


4.9 


6.0 


6.9 


8.1 


8.9 


2200 


3.9 


4.5 


5.4 


6.6 


7.6 


8.8 


9.7 


2400 


4.2 


4.9 


5.9 


7.1 


8.2 


9.5 


10.5 


2600 


4.5 


5.3 


6.3 


7.7 


8.9 


10.3 


11.4 


2800 


4.9 


5.6 


6.8 


8.2 


9.5 


11.0 


12.1 


3000 


5.2 


5.9 


7.2 


8.7 


10.0 


11.6 


12.8 


3200 


5.4 


6.3 


7.6 


9.2 


10.6 


12.3 


13.5 


3400 


5.7 


6.6 


7.9 


9.7 


11.2 


12.9 


14.2 


3600 


5.9 


6.9 


8.3 


10.1 


11.7 


13.4 


14.8 


3800 


6.2 


7.1 


8.7 


10.5 


12.2 


14.0 


15.4 


4000 


6.4 


7.4 


9.0 


10.9 


12.6 


14.5 


16.0 


4200 


6.7 


7.7 


9.3 


11.3 


13.0 


15.0 


16.5 


4400 


6.9 


7.9 


9.6 


11.7 


13.4 


15.4 


16.9 


4600 


7.1 


8.1 


9.8 


12.0 


13.8 


15.8 


17.4 


4800 


7.2 


8.3 


10.1 


12.3 


14.1 


16.2 


17.8 


5000 


7.4 


8.4 


10.3 


12.5 


14.3 


16.5 


18.2 


5200 


7.5 


8.6 


10.5 


12.8 


14.6 


16.8 


18.5 


5400 


7.6 


8.7 


10.6 


12.9 


14.8 


17.1 


18.8 


5600 


7.7 


8.8 


10.8 


13.1 


15.0 


17.3 


19.0 


5800 


7.7 


8.9 


10.9 


13.2 


15.1 


17.5 


19.2 


6000 


7.8 


8.9 


10.9 


13.2 


15.2 


17.6 


19.3 



10' 



12" 



14' 



20' 



24' 



24' 



30' 



These are the minimum allowable pulleys for the above thickness belts. 
For Belt Speeds Over 6000 Feet Per Minute Consult a Leather Belting Manufacturer. 



78 



LEATHER BELTS 



Diameter 
Small 
Pulley 
Inches 



TABLE II 
Correction Factor for Small Pulley Diameter 



Up to 10' 
Tight Side 

Above Below 



CENTER DISTANCE IN FEET 

15' 20' 25' and Over 

Tight Side Tight Side Tight Side 

Above Below Above Below Above Below 



2" 


.37 


.37 


.38 


.41 


.37 


.43 


.37 


.44 


2%" 


.41 


.41 


.43 


.46 


.41 


.48 


.42 


.49 


3" 


.45 


.45 


.48 


.52 


.48 


.54 


.48 


.55 


3y 2 " 


.49 


.49 


.53 


.57 


.53 


.59 


.53 


.60 


4" 


.53 


.53 


.58 


.63 


.59 


.65 


.59 


.66 


4y 2 " 


.56 


.56 


.61 


.66 


.62 


.68 


.62 


.70 


5" 


.59 


.59 


.65 


.70 


.66 


.72 


.66 


.74 


5'/ 2 " 


.60 


.60 


.66 


.72 


.67 


.74 


.68 


.76 


6" 


.62 


.62 


.68 


.74 


.69 


.76 


.70 


.78 


7" 


.64 


.64 


.70 


.76 


.71 


.78 


.72 


.80 


8" 


.66 


.66 


.72 


.78 


.73 


.80 


.74 


.82 


9" 


.67 


.67 


.73 


.79 


.74 


.81 


.75 


.83 


10" 


.68 


.68 


.75 


.81 


.76 


.83 


.77 


.85 


11" 


.69 


.69 


.76 


.82 


.77 


.84 


.78 


.86 


12" 


.70 


.70 


.77 


.83 


.78 


.86 


.79 


.88 


13" 


.71 


.71 


.78 


.84 


.79 


.87 


.80 


.89 


14" 


.72 


.72 


.79 


.85 


.80 


.88 


.81 


.90 


15" 


.73 


.73 


.80 


.86 


.81 


.89 


.82 


.91 


16" 


.74 


.74 


.80 


.87 


.81 


.89 


.82 


.91 


17" 


.74 


.74 


.81 


.88 


.82 


.90 


.83 


.92 


18" 


.75 


.75 


.82 


.89 


.83 


.91 


.84 


.93 


20" 


.75 


.75 


.83 


.90 


.84 


.92 


.85 


.94 


22" 


.76 


.76 


.84 


.91 


.85 


.93 


.86 


.95 


24" 


.77 


.77 


.85 


.92 


.86 


.94 


.87 


.96 


30" 


.79 


.79 


.87 


.94 


.88 


.96 


.89 


.98 


36" 


.80 


.80 


.88 


.95 


.89 


.98 


.90 


1.00 



For pivoted base drives where tight side of the belt is away from the pivot 
shaft, do not use these tables but consult a Leather Belting Manufacturer. 




79 



PLANT MAINTENANCE MANUAL 



Table III — Service Correction Factors 

Select the one appropriate factor from each of the five divisions in Table HI. 



1. ATMOSPHERIC CONDITION: 

Clean, scheduled maintenance on large drives 1.2 

Normal 1.0 

Oily, wet, or dusty 7 

1. ANGLE OP CENTER LINE: 

Horizontal to 60 degrees from horizontal 1.0 

60 to 75 degrees from horizontal 9 

75 to 90 degrees from horizontal 8 

3. PULLEY MATERIAL: 

Fibre on motor and small pulleys 1.2 

Cast iron or steel 1.0 

4. SERVICE: 

Temporary or infrequent 1.2 

Normal 1.0 



Important or continuous 8 

5. PEAK LOADS 

All electric motor drives 

Motor pulley diameters— 3" to 

4" to 

5" to 

6" to 

11" to 

14" to 



31/.". 
4Va". 

10"... 
13"... 
17"... 



.5 

.55 

.58 

.6 

.63 

.65 

18" to 23" 68 

24" to 30" .7 

All other drives 

Steady belt loads 1.0 

Jerky belt loads .,.. 8 

Shock and reversing belt loads 6 



INSTALLATION 

ALIGNMENT — Align shafting and pulleys 
correctly so that belt will not run off pulleys 
on one side or rub or climb flanged or step- 
cone pulleys. 

PULLEYS — See that pulleys are balanced 
and free from vibration. Use pulley as large 
in diameter as practical. 

JOINT— Where possible use endless belts. 
Where belt lacings or metal fasteners are 
used, be sure ends of belt are cut square and 
lacings or fasteners are installed in accord- 
ance with directions furnished by manufacturer. 

Lacing a Belt 

Single Row Method — Punch one row of 
holes in each end of the belt and uniformly 
spaced across its width. Sufficient space 
should be left between the holes and the 
edges to prevent tearing. 

Butt ends of belt together with their pulley 
sides up. Put lace down through holes No. 3 
and No. 8 from the pulley side, drawing ends 
of lace even. (See illustration.) 

Continue lacing as follows: 





Put End A 




Up 




Down 


through 




through 


3 




8 


4 




9 


5 




10 


5 




10 


4 




9 


3 






Cut slit with awl at NV2" 


back of hole No. 


3 and push lace through. Cut off the ends of 




Pulley side 



9 



WM 



f 



Outside 



80 



LEATHER BELTS 



the lace a short distance from belt surface, 
then slightly cut the stub end at the belt, twist 
and hammer down. 

Put End B 

Up Down 

through through 

7 2 

6 1 

6 1 

7 2 
8 

Cut slit with awl at N back of hole No. 8 
and fasten as for end A. 

The illustration shows five holes to each 
row. The method is the same for any odd 
number of holes— always start with the center 

Running Direction 

Care should always be exercised to have 
the outside feather edge of the laps faced 
away from the direction in which the belt 
runs. This tends to protect the outside points 
of the lap if struck by guards, guides or shift- 
ers or from being opened up due to windage. 
On single ply belt the grain side should be 
next to pulley. Wherever possible arrange for 
the slack side of the belt to be on top to pro- 
vide greater arc of contact with the pulleys. 

Putting Belt on Pulleys 

Use care in forcing an endless belt over the 
pulleys so as not to put a crook in it. Tempo- 
rarily shorten the center distance between the 
pulleys by means of motor slide rail, or loos- 
ening hanger bolts, etc. 

Tension 

For best results leather belting should be 
run with the least tension needed to transmit 
the load without slipping. If belt is run too 
slack it will slip causing the surface to glaze 
then crack and peel. If too tight, it will put 
unnecessary load on bearings. 

Belt Fasteners 

While a flat belt made endless either by its 
manufacturer or on the job, is in most cases 
desired, there are many drives where belt 
fasteners are not only convenient, but neces- 
sary. Fasteners selected for use should be 
simple and easy to install, should be smooth 
running and not pound when passing over 
the pulley, and should have ample strength 
and a long life. Whatever type of fastener is 
used, whether it be plate and rivet, steel wire 
hook, hinged pressed steel, or leather or wire 
laces, the installation directions furnished by 
the manufacturer should be followed carefully. 




Pulley side 



Belt Fasteners 



M 




WH 




hot 

1AJUV 

ura 




81 



PLANT MAINTENANCE MANUAL 



MAINTENANCE 

ALIGNMENT — Check alignment of drive at 
least once a year. See that belts are not rub- 
bing against machine guards or other obstruc- 
tions, and that belt tension is correct. 

A crooked belt may be the cause of a belt 
running off the pulley at one side. To check 
whether the cause is due to a crooked belt 
or alignment, turn the belt inside out or end 
for end. If it continues to run on the same side 
of the pulley as belore, the fault is in the 
alignment and not the belt. 





TO CHECK ALIGNMENT OF SHAFTS - *• 
Check shafts with level. 
Use a string stretched tightly between the 
shafts and a large square to determine if 
shafts are parallel. 

TO CHECK ALIGNMENT OF PULLEYS - 
Stretch a string along edges of pulleys. If 
pulleys are same width, string should touch 
lightly at 4 points — A, 8, C, and D. If one 
pulley is narrower than the other, string 
should be at same distance from narrow 
pulley at points A and B. If possible give 
pulleys a half turn and check. 



Keep Belts Clean 



To remove oil or grease from a belt give it 
a thorough scrubbing with a solution of one 
part carbon tetrachloride to three parts un- 
leaded gasoline using a stiff jute brush. If 
carbon tetrachloride is not available, the belt 
can be scrubbed or soaked in any of the 



cleaning fluids used by dry cleaning estab- 
lishments. Because of fire hazard, cleaning 
and soaking should always be done in an 
open space or where there is plenty of ven- 
tilation. Be careful when working with any 
cleaning fluid. Redress belt after cleaning. 




82 



LEATHER BELTS 



Belt Dressing 



Use a belT dressing approved by the belt 
manufacturer and designed to supply the nec- 
essary currier's oils which may have been 



lost in use or during cleaning. Under normal 
conditions belts should be dressed every 3 to 
6 months. 




Fasteners 



Renew worn fasteners or lacings before 
-they cause breakage or tearing. Use lacings 
and fasteners of the size recommended by 
the manufacturer and install according to his 
directions. When installing a new belt, never 
use the old one to determine the proper 



length of the new one. To determine the 
length for a new belt, reduce pulley center 
distance to a minimum. Then take steel tape 
measurement around the outside of the pul- 
leys. In cutting new belt make proper allow- 
ance for initial stretch— usually Vk-in. per ft. 




Laps 



If cemented laps show signs of opening, 
stick them down immediately using a belt ce- 
ment approved by the belt manufacturer. Ap- 



ply the cement carefully making sure that the 
instructions furnished by manufacturer are fol- 
lowed closely. 




83 



PLANT MAINTENANCE MANUAL 



Pulleys 

See that pulleys are in good condition and crown may be the cause of belts running off 

tight on their shafts. Fiber pulleys should be center on motor pulleys, so be very particu- 

reccowned when they become worn. A worn lar about this point. 





84 




CHAPTER 9 



RUBBER BELTS - FLAT AND V 



In the construction of flat rubber belts, the 
rubber is pressed into the fabric by running 
it through a calender or set of heated rolls. 
These impregnated canvas layers or plies are 
then laid out with layers of rubber compound 
sandwiched between them. The rubber and 
fabric are then placed together under a steam 
heated press, during which process the rub- 
ber becomes vulcanized and bonds all the 
plies and cords together, forming the finished 
belt without the aid of sewing or stitching of 
any kind. 

The firmness and elasticity of vulcanized 
rubber, allowing it to be useful as a cushion, 
gives to the belt maker a freedom in design. 
As any belt bends around the pulleys in a 
drive its pulley side is compressed, its outside 
is stretched and, at some place in between— 
within the belt material — there is no stretch 
and no compression due to bending. This 
place in the belt is called the neutral axis or 
pitch line. 

Since a rubber belt gets none of its strength 
directly from the rubber but from the fabric 
or cord, the life of a rubber belt depends in 
part upon the proper location of the strength 
member. The strength of cord and fabric is 
deteriorated by successive compressions and 
tensions resulting in raveling of the weave or 
twist. It is therefore the practice to concentrate 
the strength giving part (cord and fabric) of 



the belt at or near the neutral axis where the 
least change in stress occurs. 

When, as in the case of plied fabric belts, 
this is not possible, stresses are balanced on 
each side of the neutral axis by installing plies 
of different lengths as the belt is made up on 
the table. Such construction is called "com- 
pensated". Thus, while rubber affords great 
latitude and choice in the distribution of 
stresses and strains in the belt section, only 
high class engineering design and manufac- 
turing methods will insure a first quality rub- 
ber belt. 

Rubber belts are built up, according to their 
type of impregnated cotton duck plies, or 
cords, or both, wholly or partly surrounded 
by rubber compound. Cotton duck ply con- 
struction may take any type of belt fastener 
and may also be made endless at the factory. 

The basic constructions are raw edge, 
folded edge and cord, with many possible 
combinations. The folded edge type provides 
an envelope covering for the belt, giving it 
protection against atmospheric effects and the 
wear of flanges, guides and shifters. 

Cover seams are now lapped, in good 
practice, and are sealed with a strip of vul- 
canized rubber over a flush joint. The cover 
seam, however, is not run against the pulleys 
unless necessary. In the cord belt, the multiple 
ropes or cords are held together by the rub- 



85 



PLANT MAINTENANCE MANUAL 



ber compound and fabric envelope. This belt 
is made endless at the factory and is not de- 
signed to take a fastener. 

Some manufacturers have a successful way 
of making a vulcanized field splice in both 
cord and fabric belts where conditions pre- 
clude the installation of an endless belt. The 
cords of the cord belt are all part of one 
single length wound round and round until 
the desired belt width is obtained. The single 
row cord belt is extremely flexible and well 
adapted to small pulleys. Heavy duty belts 
of this type are made with two or more rows 
of cords and also with fabric plies in com- 
bination. 






TYPES OF TRANSMISSION BELTS 



GZ3 

Open Horizontal Drive, 
Tight Side on Bottom 
(Preferred) 

Open Horizontal Drive, 
Tight Side on Top 



Crossed Horizontal Drive 
Mule Drive 



Semi-Vertical Open 
Drive - Tight Side 
on Bottom 




Short Center Drive 
with Swinging Idler 



Vertical Open 
Drive - Small 
Pulley Above 




^% Vertical Crossed t^^ mmmmmm ^K 

TT Drive - Small Ta P ered 

A Pulley Above Cone Pulle V s 

A . Open Belt 

Jffk ^9 Multiple Drive ^S| 

° ^g 



Series Drive 




Two-Pulley 
Quarter 
Turn - 
Vertical 



Three-Pulley Quarter Turn 

I— 



Shifter with 
Tight and 
Loose Pulieys 



Four-Pulley 

Quarter 

Turn 



Stepped Cone 
Pulleys 



86 



RUBBER BELTS - FLAT AND V 



ENGINEERING 



Belts 



Select proper size belt to handle the load. 
Consult the manufacturers 1 rating tables for 
correct specifications. 



Determine necessary belt length with a steel 
tape, taking measurement around pulleys when 
they are as close together as possible. 




Pulleys 

Select proper size pulleys to deliver the 
necessary machine speed and to allow a max- 
imum arc of contact. 



Belt speed should not exceed 5500 fpm. 
Use pulleys as large in diameter as practi- 
cal, in order to avoid excessive belt flexing. 
Pulley surface should have standard crown. 




Tension 

Establish a belt tension sufficient to avoid 
slippage and yet not so tight as to put an 
unnecessary strain on the bearings. 



For short-center drives" -or where ja [fluctu- 
ating load condition exists, the use of a piv- 
oted type motor base, or an idler may solve 
a difficult tension problem. 




Power Transmission 

The ability of a belt to transmit power de- 
pends on four factors: 
I. Tensions that hold the belt to the pulleys. 



2. Arc of contact of belt with pulleys. 

3. Nature of the contacting belt and pulley 
surfaces — coefficient of friction. 

4. Belt speed. 




87 



PLANT MAINTENANCE MANUAL 



USEFUL FORMULAE: 




SYMBOLS 

R.P.M. = Horsepower 

R. = Revolutions per minute 

C = Speed ratio 

L = Center distance 

d = Belt length 

H.P. = Outside diameter small pulley 

D = Outside diameter large pulley 

V = Belt velocity in feet per minute 



SPEED RATIO 

R.P.M. of high speed shaft 
" R.P.M, of low speed shaft 


LARGE PULLEY DIAMETER 

D = d X R 


BELT LENGTH \ 
L = 2C + .251 (P " d)2 + 1.57 (D + d) 


CENTER DISTANCE 


C == a + V a 2 - b; 

where a = -~- - .3925 (D + d) 
b=.126(D-d) 2 1 


BELT VELOCITY 

V = d X R.P.M. of d X .262 



For ordinary 2-pulley "open" drives the arc of contact can be determined 
from the following approximate formula: 

(D-d) 



Arc of Contact = 180° 



-60 



ARC OF CONTACT IN DEGREES FOR TWO PULLEY, OPEN DRIVES 



MHUY DIAMITH 
IININCMIS) 








DISTANCt MTWIIN PUUIY CINTIIS IN MM- 








' 












J 


4 


* 


i 


10 


19 


IS 


JO 


15 


30 


40 


so 


2» 


175 
























4* 


170 


175 


175 




















6' 


165 


175 


175 


175 


















8* 


160 


170 


170 


175 


175 


175 














10' 


155 


170 


170 


175 


175 


175 














12' 


150 


165 


170 


175 


175 


175 


175 


175 










16' 


140 


160 


165 


170 


170 


170 


175 


175 










20' 


130 


155 


160 


165 


170 


170 


170 


175 


175 








30' 


105 


140 


155 


160 


165 


165 


170 


170 


175 


175 






40' 




130 


150 


155 


160 


160 


165 


170 


170 


175 


175 




50' 




120 


140 


150 


155 


160 


165 


170 


170 


170 


175 


175 


60' 




105 


130 


145 


150 


155 


160 


165 


165 


170 


170 


175 


70' 






120 


140 


145 


150 


155 


165 


165 


170 


170 


175 


80* 






110 


130 


140 


145 


150 


160 


165 


165 


170 


170 


100' 






100 


120 


130 


135 


145 


155 


160 


165 


165 


170 



88 



RUBBER BELTS - FLAT AND V 



INSTALLATION 



Location 

Do not install a belt drive where it will be 
subject to excessive external heat, as this 
causes rapid belt deterioration. 

Install well ventilated guard ov ; er belts 
where there is any hazard to employee safety. 
See that belts are not subject to dripping 
water or oil. 

Fasteners 

Use endless belts wherever possible. If you 
are not equipped to make vulcanized splices, 
your local industrial distributor very likely can 
make them for you. 

There are many drives where belt fasteners 
are not only convenient, but necessary. Fas- 
teners should be simple, easy to install and 
smooth running, so they do not pound when 
passing over the pulley. 

Follow the fastener manufacturers' instruc- 
tion when installing. 

Be sure belt ends are cut square and that 
the correct size fasteners are used. 

Pulleys 

Make sure pulleys are free from burrs, dirt 
and rough spots. 

See that alignment of pulleys and shafting 
is correct, so that belt will not run off, or rub 
against shifters and other stationary objects. 

Putting On 

Do not force or pry belts onto pulleys, as 
this is likely to damage the carcass and there- 
by weaken the belt. 

Reduce the center distance between pulleys 
so that belt can be slipped on easily. 

Rotation 

Endless belts should run in the direction 
indicated on the outer cover. The company 
name should be on the outside, away from 
the pulleys. 

Slack Side 

Wherever possible arrange for the slack 
side of the belt to be on top, to provide 
greater arc of contact with the pulleys. 

Tension 

After the belt is centered on the pulleys, 
adjust it to the proper tension. Remember — 
too little tension will cause slippage and 
power loss; too much tension will cause ex- 
cessive belt and bearing wear. 




89 



PLANT MAINTENANCE MANUAL 



MAINTENANCE 



Tension 

Check belt tension frequently to guard 
against slippage. 

Do not "over-tighten" belt, as this results 
in excessive belt and bearing wear. Remem- 
ber—a 10% decrease in tension will increase 
the flex life of a belt more than 50%. How- 
ever, slippage will also shorten the useful life 
of the belt. 



<; 



Alignment 

Check alignment of pulleys and shafting: 
periodically, to make sure belts are running 
true. 




Clean Belts 

Keep belts clean by wiping off with a dry 
rag. 

If necessary, scrape the belt lightly, taking 
care not to damage the surface. 

Keep oil and grease off belts, as these ma- 
terials will quickly ruin a belt. 

The hard, glazed surface that sometimes 
forms on the pulley side of belts, can be re- 
moved by holding a cloth, lightly dampened 
with 50-50 alcohol and glycerin, or suitable 
petroleum solvent, against this side of the 
belt while it is running. 




Dressing 

As a general rule rubber belts require no 
dressing. If it is absolutely necessary to use a 
dressing, in order to prevent slippage, use a 
dressing recommended by the belt manufac- 
turer. 




Fasteners 

Renew belt fasteners before they become 
worn out and break. Check fasteners fre- 
quently to guard against unnecessary damage 
to belt structure. 




Removing Belts 

Remove belts carefully, preferably by re- 
ducing the belt tension and hand-turning the 
pulleys. Belts thrown from fast moving pulleys 
often suffer sharp twists or bends which injure 
the belt structure. 




Storage 

Rubber belts should be stored in dry, cool 
and dark rooms, away from heat and sun- 
light. 

Do not hang belts in a way that will cause 
sharp bends or damage to the belt structure. 




90 



RUBBER BELTS - FLAT AND V 



RUBBER V-BELTS 



The following general features are usually 
present in the standard types of V-belts: 

The pulling element or the part of the belt 
which actually carries the tension consists of 
a number of high-strength cords which are 
held in place and prevented from chafing by 
the application of pure gum rubber or proper 
synthetics. In certain cases the individual cords 
are impregnated with pure gum rubber or 
proper synthetics and Jhen surrounded entirely 
by a thick layer of the same substance. The 
Impregnating and embedding material used in 
this strength section of the belt must be highly 
heat-resistant, tough, and yet quite resilient, 
so as to permit necessary flexing. 

The remaining cross-section of the belt is 
usually made up of alternate layers of vulcan- 
ized rubber and canvas, or rubber containing 
enough filler to give it sufficient rigidity to 
withstand the compression due to the pressure 
against the sides of the grooves. If the belts 
are designed for use in V-flat drives as well 
as the regular V-V drive, then the compression 
section of the belt must be stiff enough to 
withstand the pressure on the flat pulley and 
it must also be able to transmit the forces from 
the underside of the belt to the load-carrying 
cords. 

The section is usually trapezoidal in shape 
and the angle between the two sides is be- 
tween 38 and 44 degrees. 

The entire belt as made by some manufac- 
turers is supported and protected by a canvas 
and vulcanized rubber casing which gives 
added stability and also serves to keep out 
foreign materials. 

Types of Construction 

1. Alternate layers of canvas and rubber 
are vulcanized together to give the desired 
thickness. The endless belts are shear cut from 
the material made up in form of a cylinder or 
tube. This type of construction gives good 
lateral stiffness, but the exposed cut edges of 
the canvas are very apt to wear rather rapidly 
and there is some danger of ply separation. 




2. The strength section of this belt is made 
up of fairly large gum-saturated cords which 
are supported in a layer of pure gum rubber. 
Above and below the strength section are 
layers of rubber of fairly good stiffness, but 



pliable enough to permit the necessary bend- 
ing action. The entire section is encased in 
a vulcanized rubber and cotton duck cover. 
Uniform trapezoidal cross-section is obtained 
by carrying out the vulcanizing process in a 
mold. 




3. This is similar to number 2 above except 
that a smaller diameter cord is used to pro- 
vide the strength-carrying capacity and these 
cords are located more nearly in the mid- 
position between the top and bottom of the 
section. 




4. In this construction the sidewalls of the 
belt are molded in a concave shape so that 
the sides of the belt will be straight when bent 
around the pulley. The strength section is 
made up of gum-impregnated cords and the 
compression section is composed of alternate 
layers of vulcanized rubber and duck. This 
type of construction in the compression sec- 
tion makes the belt particularly adaptable for 
use in V-flat drives and also gives good lateral 
stiffness in the grooves. 




5. Twin cable construction of cotton cord 
grouped into heavy cables, molded into a 
solid rubber belt compound at the pitch line. 
This type is particularly adaptable to heavy 
duty belts where strength and flexibility is a 
necessity. 




6. This type of corrugated construction is 
designed primarily to allow a higher degree 
of flexibility without the sacrifice of lateral 
stiffness. 



V iM ir- 




91 



PLANT MAINTENANCE MANUAL 



7. Another type of construction is the belt 
made up of laminated links which can be 
easily added or subtracted to adjust the 
length of the belt. It lends itself to making up 
belts of any length and to ease tension ad- 
justment and installation, particularly on drives 
with outboard bearings. 




Sheave Construction 

The grooves in a sheave for V-belts must be 
cut very accurately in order to afford maxi- 
mum contact with the belts. In the case of 
multi-strand sheaves, each groove must be 
identical with the others on the pulley so that 
the tension will be equally distributed in the 
several strands. The angles of the grooves are 
made smaller in the case of smaller sheaves 
so as to gain a greater wedging action. 

Sheaves are generally made of either solid 
cast iron with cut grooves, or of a pressed 
steel construction. Either type can be obtained 
with interchangeable hub bushings to accom- 
modate different sized shafts. 

Variable pitch diameter sheaves are also 
available in which the pitch diameter can be 
changed to give a limited range of speed 
variation. 



(a) Pressed steel, single 
groove sheave. 




(b) Pressed steel, multi- 
groove sheave with inter- 



changeable hub 



(c) Web type, 
cast iron sheave 
with offset hub. 





Closed position Open position, 
maximum pitch minimum pitch 

Id) Cast iron, diameter diameter. 

arm type sheave 

with central hub < e > Variable pitcn diameter sheave. 



ENGINEERING 

V-Flat Drive 

In many caes V-flat drives can be used 
economically, especially where there is a 
large speed ratio. A V-belt from a driven 
sheave is used to turn a large flat pulley 
where the speed ratio is 3:1 or greater, and 
the center distance is approximately equal 
to the diameter of the flat pulley. Belts used 
on V-flat drives have about 70% their normal 
rating. 



I 



GROOVED PULLEY 

FLAT PULLEY 



Tension 

A pivoted or spring type motor base can 
often be used advantageously to assure cor- 
rect belt tension, particularly on short-center 
drives, or where the load undergoes sudden 
variations. 




PIVOTED iASE TYPES 



Sheaves 

Specify sheaves of the proper diameter to 
provide the correct machine speed, selecting 
sheaves of as large a diameter as practical. 
Be sure tha* belts and sheave grooves match. 
Belt speed should not exceed 4500 fpm, nor 
be less than 100 fpm. 

Center distance between sheaves should 
not exceed three times the diameter of the 
larger pulley,- or be less than the diameter of 
the larger pulley. 

Pulley ratio should not exceed 8:1. 



DIMENSIONS OF A SHEAVE 




OUTSIDE DIAMETER 



92 



RUBBER BELTS - FLAT AND V 



ENGINEERING 

I = 2C + 1.57(0 + d) + 



(0 - d)» 



Center ditfoiK* — 

C = A + VA»-B 

wh«r« A = - 0.3925 (0 + d) 

B = 0.123d (D-d)» 



Belts 

•Select the proper size and number of belts 
to handle the load. Consult manufacturers' 
rating tables for correct specifications. 



L = length of bolt in inches. 
C = center distance in inches 

D = pitch diameter of 4arge pulley Tn inches, 
d = pitch diameter of small pulley in inches. 



Follow manufacturers' recommendations for belt sizes. 
The following table provides a rough check. 



MOTOR SPEED-RPM 



Horsepower 1750 



1160 



870 



690 



575 



490 



435 



V2 

% 

1 

l'/2 

2 
3 
5 

7V2 

10 

15 

20 

25 

30 

40 

50 

60 

75 
100 
125 
150 
200 
250 
300 and above 



A 

A 

A 

A 

A 

A 
B (or A) 

B 

B 

B 
BorC 
C (or B) 

C 

C 

C 

C 

C 

C 



A 

A 

A 

A 

A 

A 
B (or A) 

B 

B 
BorC 
C (or B) 

C 

C 
CorD 
CorD 
CorD 
D (or C) 

D 

D 

D 

D 

D 



A 

A 

A 

A 

A 
B (or A) 

B 

B 
BorC 
C (or B) 

C 

C 

C 
CorD 
CorD 
D (or C) 

D 

D 

D 

D 

D 

D 



D 

D 

D 

D 

D 

D 

D 
DorE 
DorE 
E (or D) 

E 

E 



D 

D 

D 

D 

D 

D 
DorE 
E (or D) 
E (or D) 

E 

E 

E 



APPROXIMATE SIZE OF STANDARD V-BELT SECTIONS 




93 



PLANT MAINTENANCE MANUAL 



MAINTENANCE 



Belts 



V-belts used on multi-groove sheaves should 
all be the same length. Many companies pro- 
vide matched sets of belts which have been 



factory checked for identical lengths. 

Make sure belts are the correct size for the 
sheave grooves and for the kind of load to 
be handled. 




Sheaves 

Make sure the grooves in the sheaves ure 
all the same size. 

See that sheaves are clean and free from 



burrs or rough spots. 

The sheaves must be very accurately aligned. 
Key sheaves properly to the shafts, so that 
there will be no side travel. 




Putting On 

Decrease the center distance between 
sheaves so that belts can be slipped in place 
easily. Do not pry or force belts onto sheaves, 
as this is apt to damage the structure. 



Arrange belts on sheaves so that the slack belts. 



side of each belt will be on the same side 
of the drive. In this way the belts will all 
tighten up equally. ' 

Run the machine for a few minutes to set 
the belts, then stop the drive and retighten 




94 



RUBBER BELTS - FLAT AND V 



Tension 

The belt tension should be increased until 
there is no slip. Do not over-tighten, as this 
puts an unnecessary strain on the bearings. 



During the first 48 hours operation the ten- 
sion should be watched carefully because the 
initial stretch is being taken out of the belts 
and they are settling into the sheave grooves. 



s 


<> 


9 ( 




i; 




te «S5bm 




*>' 





























Location 

Do not install V-belts near heaters, or where 
the temperature registers more than 140 de- 
grees. 



See that no oil or water drips on belts. 

Install guards around drives that might be 
a hazard to employee safety. Be sure that the 
belt guard permits adequate ventilation. 




95 






CHAPTER 10 



TRANSMISSION CHAINS 



Chain drives are an effective and efficient 
form of flexible gearing for the transmission 
of power. They deliver practically all — 98 to 
99 per cent — the power applied. 

Modern chain drives are applicable to al- 
most any kind of industrial drive from frac- 
tional horsepower up to 5,000 horsepower. 
Speeds of drives may range from one revolu- 
tion per minute, or less, up to 8,000. Chains 
are used for transmitting power from prime 
mover to machine or line shaft, from shaft to 
machine, and from shaft to shaft on machinery. 

Since these chains operate over toothed 
wheels, slippage is eliminated. Furthermore, 
the flexibility and strength of these drives en- 
able them to withstand shock loads and severe 
conditions of operation. 

In addition to power driving, these chains 
are adaptable to conveying installations, for 
counter weight support, and to timing, con- 
trolling and regulating mechanisms. 

Transmission chains are high precision prod- 
ucts and some kinds are available in both 
American Standard and non-standard sizes. 
The metals most commonly used in chains and 
sprockets are alloy steels, cast or forged, and 
iron, cast or malleable. Where drives are 
subject to heat or to corrosion by liquids or 
fumes, or where conditions call for a metal 
with non-magnetic properties, chains and 
sprockets of stainless steel, bronze or other 
special materials are supplied. 



Selecting The Proper Drive 

In selecting the right kind and size of chain 
for a given drive, it is best to consult chain 
manufacturers for their experienced recom- 
mendations. The sort of information desired 
by manufacturers for proper advice is dis- 
played elsewhere. 

The makers of transmission chains have 
very complete tables and diagrams for use in 
choosing the correct pitch, width and amount 
of chain and the number of teeth on, and 
size of the sprockets for an installation. These 
data are based upon the horsepower require- 
ments and certain service factors for the vari- 
ous load conditions. 

In most cases it is desirable to select the 
chain with the smallest pitch that will transmit 
the desired horsepower at a speed within the 
specified range. Generally speaking, the 
smaller the pitch and the more the number of 
teeth on the sprockets, the more quiet will be 
the drive. 

Ordinarily, small driving sprockets with less 
than, say, 17 teeth should be avoided, al- 
though sprockets with fewer teeth are used 
for low speed drives. 

In the case of driven sprockets, the number 
of teeth depends upon the desired speed of 
that sprocket and upon the driving sprocket 
being used. The maximum speed ratio advis- 
able is 10 to 1. 



96 



TRANSMISSION CHAINS 



For the proper selection of a suitable chain 
drive, the manufacturer should be given the 
following information: 

1. Power source — 

Kind: electric motor, steam engine, internal 

combustion engine, line shafting. 
Amount, in horsepower. 

2. Driven unit— kind of equipment; speed. 

3. Service conditions — continuous, intermit- 

tent, standby; hours of operation per 
day. 

4. Character of load— steady or pulsating. 

5. Speeds — ratios; if variable, maximum and 

minimum. 

6. Shafts — rotating speeds,- diameters; center 

distances, and whether fixed or adjust- 
able; key seat dimensions. 

7. Location— space limitations,- position or an- 

gle of drive centerline,- environment: 
any unusual features. 

8. Encasement of drive — requirements for 

proper lubrication and protection 
against dirty operating conditions. 

CALCULATING CHAIN LENGTHS 

The length of a chain in pitches can be 
calculated by several special formulas, one 
form of which is as follows: 



VALUES 



FOR K 
CHAIN 



FOR COMPUTING 
LENGTHS 



in 


L = 2C +- 

which 


T + 1 _|_ K (T - 
2 C 


t) 1 


C 


= 


center distance between shafts in pitches. 


T 


= 


number of teeth 


in large sprocket. 




1 


= 


number of teeth 


in small sprocket. 




K 


= 


constant based on value of "" 

1 








obtained from 


the accompanying 


table. 



To obtain the length in inches, multiply by 
the pitch of the chain. 

L must be a whole number, as a chain can- 
not contain a fractional part of a pitch. If it 
does contain a fraction, use the next higher 
whole number. 

Note: The above formula is also written with 
the letters "N" and "n" representing the num- 
ber of teeth in the large and the small 
sprocket, respectively. Also, in some cases val- 
ues, which are designated by the letters "C" 
or "K", have been worked out for K (T— t) 2 
and tabulated for convenience. Furthermore 
"D" may be used to represent the center dis- 
tance between shafts, and "S" may be sub- 
stituted for T -f- 1. 



T-t 




T - t 




C 


K 


C 


K 


0.2 


.02533 


4.35 


.02653 


0.4 


.02534 


4.40 


.02656 


0.6 


.02535 


4.45 


.02660 


0.8 


.02536 


4.50 


.02663 


1.0 


.02538 


4.55 


.02667 


1.2 


.02540 


4.60 


.02671 


1.4 


.02543 


4.65 


.02675 


1.6 


.02547 


4.70 


.02679 


1.8 


.02550 


4.75 


.02683 


2.0 


.02555 


4.80 


.02687 


2.1 


.02557 


4.85 


.02691 


2.2 


.02560 


4.90 


.02695 


2.3 


.02562 


4.95 


.02699 


2.4 


.02565 


5.00 


.02703 


2.5 


.02568 


5.05 


.02708 


2.6 


.02571 


5.10 


.02713 


2.7 


.02574 


5.15 


.02718 


2.8 


.02577 


5.20 


.02723 


2.9 


.02581 


5.25 


.02728 


3.0 


.02584 


5.30 


.02733 


3.1 


.02588 


5.35 


.02739 


3.2 


.02592 


5.40 


.02744 


3.3 


.02596 


5.45 


.02750 


3.4 


.02600 


5.50 


.02756 


3.5 


.02605 


5.55 


.02762 


3.60 


.02610 


5.60 


.02769 


3.65 


.02612 


5.65 


.02775 


3.70 


.02615 


5.70 


.02782 


3.75 


.02617 


5.75 


.02789 


3.80 


.02620 


5.80 


.02796 


3.85 


.02623 


5.85 


.02804 


3.90 


.02625 


5.90 


.02812 


3.95 


.02628 


5.95 


.02820 


4.00 


.02631 


6.00 


.02828 


4.05 


.02634 


6.05 


.02838 


4.10 


.02637 


6.10 


.02848 


4.15 


.02640 


6.15 


.02859 


4.20 


.02643 


6.20 


.02871 


4.25 


.02646 


6.25 


.02884 


4.30 


.02649 


6.30 


.02901 



PROPER MAINTENANCE PROLONGS 

THE LIFE AND EFFICIENCY 

OF CHAIN DRIVES. 



97 



PLANT MAINTENANCE MANUAL 



KINDS OF 

There are various kinds of industrial trans- 
mission chains. Two principal types are rol- 
ler and silent. Roller chain drives consist of a 
series of uniformly spaced roller links con- 
nected together by pin links. Silent chain drives 
are made up of a series of inverted tooth 
links which are joined by pin arrangements 



CHAINS 

which allow articulation of the joints to en- 
gage the sprockets. 

Other kinds of chains are block, extended 
pitch, combination and so forth. Most of these 
are adaptations of the basic roller form of 
chain. There are likewise many varieties of 
both roller and silent chain constructions. 



Roller 

Roller chains are made up of a series of 
roller links joined by pin links. 

A roller link comprises two rollers, two 
bushings and two link plates. The rollers en- 
gage and bear against the sprocket teeth. 
The bushings are press-fitted into the pitch 
holes so that they do not turn in the side or 
roller link plates. 

In engaging the sprocket wheels, the rollers 
fold into a rolling mesh with the teeth and 
seat at the bottom of the space between the 
teeth. The load is distributed among several 
teeth. 

Pin links carry two pins and two pin link 
plates. The pins fit into the bushings in the 
pitch holes of the roller links. The pins and 



Chains 

bushings are the bearings of the chain. 

Chain pin ends are riveted or cottered. 
Connecting link pins are cottered or grooved 
for locks of various sorts. 

Roller chains, for which American Stan- 
dards have been established, are used in a 
single strand or multiple strands as required. 
The latter are of the same construction as the 
former, except that the pins extend through 
the several strands which may number 2, 3, 4, 
6, 8, 10, 12 or more. These multiple assem- 
blies are more durable and effective than 
the same number of single strands run paral- 
lel in a group, so the latter is not recom- 
mended. Common pitches of roller chains are 
from '/ 4 inch to 2V2 inches. 



rLOAD, 




Roller Chain 

Correctly designed and accurately cut 
sprocket teeth are essential to good roller 
chain drives. Sprockets may have no hubs, a 
hub on one side, hubs on both sides, or the 
hub may be attached by bolts to the sprocket. 
When the hub is an integral part of the wheel, 
the sprocket may be either of solid web con- 
struction or with spokes, depending upon the 

98 



Sprockets 

size. Sprockets are also made to meet special 
requirements. 

Hubs and sprockets of split construction are 
available where installation without moving 
the shafts or bearings is necessary. The ma- 
terials from which sprockets are made are 
iron or steel, hardened or unhardened, de- 
pending upon the duty to be performed. 



TRANSMISSION CHAINS 




Silent 

Silent chains consist of a series of inverted 
tooth links or laminations which mesh into 
place and seat between the sprocket teeth. 
Engagement is a gradual sliding one. 

The links are joined by bushed or unbushed 
round pins or combinations of seat and rocker 
pins. In most cases the meshing links are lo- 
cated on the inside face of the chain, with 
the outside face smooth. Silent chains are 
also made, however, with sections of the links 
alternately tooth-side down and tooth-side up, 
where both faces must mesh with sprockets in 
order to transmit power, engage idlers, or 
reverse the direction of shafts. 

These chains come in a wide variety of 



Chains 

widths, connecting link projections, sprocket 
face widths, guide groove widths and depths, 
and sprocket tooth heights. 

The running position of the chain is main- 
tained in several ways. Chains may be guided 
on their sides by plain untoothed link plates 
or by shrouds. Another means is to set a row 
of guides in the center of the chain. Some 
chains do not carry guides, in which cases the 
sprockets are flanged for the purpose of pos- 
itioning the chain. 

Pitches of silent chains usually range from 
3/16 inch to 3 inches, and widths of a wide 
variety in all pitches may be obtained from 
manufacturers. 




Silent Chain Sprockets 



The tooth arrangements of sprockets for 
silent chains differ, of course, from those used 
with roller chains. Small sprockets are usually 
steel hardened for wear resistance and may 
be forged or cast. Sprocket types include 
those without hubs, with hub on one side, and 
with hubs on both sides. Smaller sizes usually 



are of web construction while the large ones 
commonly have spokes. 

Where necessary or desired for installation 
without having to move shafts or bearings, 
sprockets of the split type are available. An- 
other kind of special sprocket is an equaliz- 
ing spring type for use where starting torque 



99 



PLANT MAINTENANCE MANUAL 



is high or where fhe drive is otherwise sub- 
ject to extreme shocks or pulsations. Spring 



sprockets may be furnished in split construc- 
tion also. 




Block And 

Block chains are used for smaller transmis- 
sion drives, supporting counterweights, bear- 
ing oilers and light conveying. They may be 
used over sheaves or pulleys as well as on 
sprockets. 

They are commonly made up of a series of 
center blocks connected by pin links. Center 
blocks may be solid or laminated. 



Other Chains 

Conveyor chains are not intended for 
power drives and operate at relatively slow 
speeds. Their pitch is often longer than that of 
standard power drives. Designed for convey- 
ing services, they may be obtained with 
straight or bent lug side plates, extended pins, 
flat top plates, pusher attachments or other 
features. 




INSPECTIONS 

Chain drives should be inspected at regular 
intervals for alignment, adjustment and lubric- 
ation. This practice is most important because 
many drive troubles are caused by incorrect 
usage rather than defective materials. 

A trouble shooting chart is presented in 
this chapter. 



Alignment 

Installation of a chain drive is quite simple. 

Two most important precautions are to make 
certain that both the chain and the sprockets 
are accurately aligned and that the shafts 
are parallel. The use of a spirit level wiH show 
whether the shafts are parallel. 

Shafts are parallel if the distance between 



100 



TRANSMISSION CHAINS 



TROUBLE CHART 


TROUBLE 


WHAT TO INSPECT 


Breaks 

Chains 


Pitch or size — wrong for speed. 
Shocks— loads applied suddenly. 
Chain or sprocket — worn or inaccurate. 
Corrosion — water or moisture in housing. 


Sprocket 
teeth 


Chain clearance — insufficient 
Obstructions — foreign matter in case. 
Chain or sprocket — badly worn. 


Chain Action: 

Climbing 
sprockets 


Sprocket teeth — badly worn, incorrect, 
or too few in mesh 

Overloads — excessive. 


Sticking to 
sprockets 


Sprockets — worn or incorrect. 


Stiffness 


Sprockets and shafts — bad alignment. 
Joints — rusted or corroded. 
Overloads — severe. 
Lubrication — improper. 


Noisy Operation 


Sprockets and shafts — bad alignment. 
Casing or bearings — loose. 
Chain or sprockets — worn. 
Lubrication — none or improper. 
Slack — too little or too much. 


Wear 

On sides of 
chain, or 
sprocket 
teeth 


Sprockets — bad aliqnment, excessive 
axial float. 

Shafts — not parallel. 



101 



PLANT MAINTENANCE MANUAL 



them is the same on both sides of the drive. 
To align the sprockets run a straight edge or 
string along the sides of both sprocket faces. 
Sprockets and keys should be tight on the 
shaft. Idler sprockets are checked for align- 
ment in the same manner as other sprockets. 
Shoe idlers, however, should be positioned so 
that they contact the face of the chain and 



so that they are also. clear ot the side plates. 

Another point to make sure of is that the 
shafts on which the sprockets are mounted 
are suitably and rigidly supported. 

When installed the chains should be fairly 
tight and with only a small amount of slack 
or sag. If the drive is vertical, special care 
must be taken to keep the tension snug. 



D = Distance between shafts, 
same on both sides. 



Spirit Level 




String or Straight Edge 

) 



m 



Connecting Chain Ends 

Connecting links are used for joining the 
two ends of a chain to form the endless drive. 
One common way to connect chain ends is by 
wrapping the terminal links about half way 
around one sprocket, or by meshing them 
on top of the larger sprocket. The sprocket 
teeth hold the chain ends in place while the 
pins are being inserted. 

The mesh should be checked carefully be- 
fore connecting together the two ends of a 
chain. 

When arrows appear on the side of silent 
chains, they indicate the direction in which 
the chain should run. If the drive is a revers- 
ing one, the arrows should point in the direc- 
tion of the heavier drive. 

The cotters of connecting links should be 
spread carefully. 



Adjustment 

It is advisable, especially in long distance 
drives, to provide some means of adjusting 
the center distance between sprockets. Such 
adjustments make it possible to compensate 
for any natural wear and take up any unde- 
sirable slack. 

If the position of the drive centers is fixed, 
the adjustment may be accomplished by the 
introduction of chain adjusters, shoes or idler 
sprockets' or rollers. They usually mesh with 
the slack span of the chain. 

In roller chain drives idlers are usually 
located on the outside of the chain, prefer- 
ably near the smaller sprocket. In silent chain 
drives the take-up would be of the sprocket 
type if it acts against the inside toothed face 
of the chain, or if the chain has teeth on both 
faces. A roller or shoe would be used if the 



102 



TRANSMISSION CHAINS 



take-up were applied to the smooth side of 
the chain. 

Sometimes double idlers are employed, one 
making contact with the tension span of the 
chain drive and the other with the slack span. 




Shortening or Lengthening Chains 

If it is desired to shorten or lengthen a 
chain drive the adjustment can be accom- 
plished by the removal, or addition, of chain 
links. 

Where an even number of links are in- 
volved, the sections may be removed from or 
introduced into the chain, as the case may 
be. Furthermore, if an old section of a chain 
is to be replaced with new chain, use two or 
four link sections, spacing them at equal in- 
terval's in the old, since new chains are 
shorter in pitch. 

If the chain is to be shortened or length- 
ened an odd number of links, use offset or 
hunting links. Offset bars are generally run 
with the closed end in the direction of travel. 

It is good maintenance practice to check 
the adjustment and alignment about one month 
after the drives are installed and again each 
six months to a year thereafter. 




Repairing Chains 

In making any repairs to chain drives, be 
sure to observe great care because these 
chains are precision assemblies with press fits 
and should not be damaged in any way. Man- 
ufacturers of chains have suitable tools for 
use in connecting, disconnecting and repair- 
ing their chains, although ordinary hand tools 
will generally suffice. 

The extent of chain wear may be judged 
by pulling the chain radially away from the 
larger sprocket, about half way around the 
arc of mesh. 

Broken or damaged parts should be re- 
placed. Replacement should be by complete 



assemblies rather than by individual parts. In 
fact, it is often advisable to install an entirely 
new chain rather than make partial repairs to 
an old one. In this connection chains that have 
worn out should be replaced promptlv. 

When making repairs, do not add a few 
lengths in any pitch. All new links should be 
added to the section through the entire width 
of the chain. 

It is possible at times to reverse worn 
sprockets. However, where the wear on the 
tooth faces or sides is considerable, and es- 
pecially if new chains are being installed, 
new sprockets should be used. Do not put 
new chains on old or badly worn sprockets. 

Properly maintained sprockets will often out- 
wear two or three chains. 

LUBRICATION 

Correct lubrication of chain drives is most 
important. For the adoption of proper lubri- 
cating materials and practices contributes 
much toward maximum service and efficiency. 

On the other hand, faulty lubrication leads 
to harmful results. A common error in this 
respect is the use of heavy oils and greases, 
unless they are melted thin and the chain is 
immersed. 

The specific lubricant to use depends upon 
the method of lubrication being employed, the 
speed of the drive and the temperature of 
operation. In general, however, a good qual- 
ity, light-bodied, neutral mineral engine or 
motor oil which will remain liquid at prevail- 
ing temperatures is recommended. Oils com- 
monly used are of grades that meet SAE Spe- 
cifications 10, 20, 30 and 40 or API Lubricants 
Nos. 2, 3 and 4 which have similar Saybolt 
Universal viscosity ranges at 100 deg. F. Suit- 
able heavier winter-type automobile trans- 
mission oils are used on some large, slow- 
moving drives. Bright pins and a black lubri- 
cant at the joints indicate that the lubrication 
has been good. 

It is always best to follow the manufacturers' 
recommendations regarding the proper lubri- 
cants. 

Methods of Lubrication 

Lubrication is accomplished by several me- 
thods — hand, splash, drip, disc, ring and 
pressure. Whatever the system the oil must 
penetrate to the pin bearings to protect 
against wear and metal-to-metal contact. Ac- 
cess to the bearings is by way of the 
clearances between link plates. 

Manual lubrication is performed with a 
spout can or brush, the oil being -applied to 
the inside surface of the lower span of chain. 



103 



PLANT MAINTENANCE MANUAL 



Centrifugal force throws the oil through the 
chain. This method is suitable for many ex- 
posed drives where the speed of operation is 
slow. It is also applicable to some higher 
speed installations where the service is inter- 
mittent or of a standby nature. 

Where slow speed drives are enclosed, the 
splash method is commonly used. Here the 
lower run of the chain passes through a bath 
in which the oil level is just high enough to 
reach the chain. Deep submergence merely 
increases the turbulence. 



In slinger type lubrication, a disc dips Into 
the oil bath and carries the adhering lubricant 
to a baffle or scraper from which it feeds to 
the chain. A ring oiler, in which a ring dips 
into the oil reservoir below and carries the 
oil to a collector for delivery to the chain, 
is another form of the dip-and-sling method. 

This system of lubrication may be used 
where service is of the heavy duty or con- 
tinuous sort. The drive, of course, must be 
enclosed and oil tight. 




«y 



SPLASH 

For medium speed drives, drip lubrication 
is quite adequate. The oil reservoir is an oil 
cup, oil pot or sight feed oiler, and the oil 
is fed through a pipe to the inside of the 
chain; the leads or drip openings may be as 
many as required to direct the oil inside the 
chain between the side plates. 



DISC 

Positive or force feed lubrication is recom- 
mended for continuous high-speed drives. A 
small pump circulates the oil into the system 
for discharge to the inside of the chain. 



1-T 




Til 


*m 


t> 




104 



TRANSMISSION CHAINS 




105 



PLANT MAINTENANCE MANUAL 



Periodic Checks 

All lubrication systems should be checked 
periodically to see that proper oil flow is 
being maintained. 

Oil reservoirs in enclosed drives should be 
cleaned and the oil changed occasionally— 
once a year is a good interval unless dirty 
operating conditions require more frequent 
changes. 

Reservoirs for drip systems should be filled 
at regular intervals. The used oil should be 
drained out of the case before it gets high 
enough to reach the chain on its low span. 
If this oil is still clean it may at times be used 
over again. 

In disc, ring or splash systems the oil reser- 
voir should be maintained to a level at which 
the chain will be shallowly, yet completely, 
immersed as it passes through the bath. 

Cleaning Chains 

Where drives operate unprotected in the 
open and conditions are dirty, chains should 
be removed periodically and thoroughly 
cleaned and relubricated. Exposed chains on 
trucks which are driven daily, for instance, 
should be cleaned each week. Daily brushing 
and oiling is recommended. 

Soaking in kerosene or other suitable sol- 
vent accompanied by a thorough scrubbing 
will produce good results. The cleaning solu- 
tion should be drained off the chain. The 
cleaned chain is then worked in the proper 
lubricant. The excess lubricant should be re- 
moved by draining and wiping. 

After reinstalling the cleaned chain, it 
should be checked for adjustment. 

When cleaning them, chains should be 
examined for uneven wear. 




Casings 

Casings protect the drive, keep machinery 
clean, promote safety and provide a housing 
for proper lubrication. By keeping "dirt out 
and oil in" the drive, these casings create 
operating conditions of the best sort. Casings 
should be used especially where dirt and 
dust prevail and where operations are at high 
speeds. 

Casings are fitted for splash, drip, disc, ring 
and pump lubrication as required or recom- 
mended. Panels or hinged sections are 
provided for easy inspection. Vents and 
breather holes and other special devices are 
supplied when advisable. In oil tight casings, 
shafts and openings are sealed against oil 
leakage. 




106 



TRANSMISSION CHAINS 



Storage 

Chains which are to be idle for an ex- 
tended period should be removed and stored. 
They may be flushed and covered with lubri- 
cant and wrapped securely; then stored 
away in bins. Chains may also be left in a 
pail of oil, if preferred. 




107 




CHAPTER 1 J 

GEAR DRIVES 



There are many gear designs and arrange- 
ments used in the transmission and speed con- 
version of power drives. Some of the common 
forms of gearing are spur, helical, herring- 
bone, bevel, hypoid and worm, and varia- 
tions and combinations of these gear types. 

In spur gears, the teeth are on the inside 
or outside surfaces of cylinders and run 
parallel with the axes of the gears. They are 
used where the shafts of the driver and the 
driven components are parallel. 

In helical gears, sometimes called spiral, 
the teeth are also on the surface of cylinders, 
but they wind around them in spiral form 
rather than parallel to the axis shaft. Helical 
gears are commonly used when the drive and 
the driven shafts are parallel or at right 
angles, or any other angles, to each other, 
but are non-intersecting. 

Herringbone gears are double helical gears 
in which the teeth are "V" shaped. This ar- 
rangement of the gear teeth counteracts any 
end thrust produced "when helical gears are 
used to connect parallel shafts." 

Bevel gears have their teeth on pairs of 
cones which mesh so as to transmit power 
between two intersecting shafts, and occa- 
sionally shafts which do not intersect. In a 
straight tooth bevel gear, all gear teeth 
planes intersect the axis of their respective 
cones. If the teeth are of the helical type, the 



gear is called a spiral bevel. Miter gears are 
bevel gears in which both center ancfles are 
45 deg. 

A hypoid gear is a special kind of skew 
bevel gear used when the axis of the gear 
shaft and that of the pinion are not in the 
same plane. 

In a worm gear the teeth of the worm wind 
around the shaft cylinder and mesh with the 
teeth on the gear which are specially cut to 
mesh with the worm teeth. With worm gears 
high speed-reduction ratios are obtainable 
between the shafts, the axes of which are 
contained in planes which are at right angles 
to one another. 

Selection 

Careful consideration should be given to 
the selection of the right gear drive for the 
specific operating conditions of each installa- 
tion. In this connection the manufacturers of 
gears and gear drives should be consulted 
for their experienced recommendations. 

Among the factors to be considered in se- 
lecting the right equipment are the following: 
the load characteristics-whether steady or 
shock; the kind of duty-daily hours of opera- 
tion and whether continuous or intermittent; 
kinds of driver and driven machines-and 
horsepower of former and that required by 
the latter; and the form of reducer drive. 



108 



GEAR DRIVES 



TYPICAL GEARS 




Spur-external 




Helical 




opiral bevel 



Worm 




Spur-internal 





Herringbone 



Hypoid 




109 



PLANT MAINTENANCE MANUAL 






ENCLOSED GEAR DRIVES 

Enclosed gear units carry such names as 
speed reducers, speed increasers, gear boxes, 
gear cases, reductors and the like. Motor re- 
ducers, gear motors and other Ijke-named 
speed reducers built into motors also belong 
in this group. 

In these self-contained, power-drive units 
•the gears are accurately installed, aligned 
and cased in an appropriate housing by the 
manufacturer at his factory. Thus, many of 
the difficulties encountered in the installation, 
operation and maintenance of open gearing 
are greatly minimized and in some instances 
actually eliminated. 

In other words, the makers of enclosed gear 
drives furnish compact, completely packaged 
gearing units for all manner of drive, speed 
conversion and power transmission applica- 
tions. 

The great majority of gear drives operate 
with remarkable efficiency. Nevertheless, most 
manufacturers of gearing issue instructions on 
the proper use, installation, alignment, lubri- 
cation, care, and other maintenance practices 
for their equipment. These instructions should 
be studied and followed carefully. 



Foundations 

Great care must be exercised in handling 
gears and pinions of all kinds in order to 
prevent distortion or other damage to the 
machine and the gear teeth. This precaution 
should be observed at all times and under all 
conditions. 

Because of their housings, enclosed gear 
drives are, of course, considerably protected 
from dirt and dust and abuse of many kinds. 
They should, therefore, not be taken apart, 
thereby permitting dirt to get into the unit. 
Neither should any slushing compound in the 
gear units be removed until they are about 
to be installed. 

Foundations for speed reducer installations 
should be rigid and substantial enough to; 
prevent vibration and to maintain alignment. 
The most satisfactory foundations are those 
of concrete, masonry or structural steel. If 
properly and rigidly designed and construct- 
ed, wood framework or timber may be used. 

Be sure to follow the manufacturer's in- 
structions for the erection, and installation of 
their units. The section on alignment gives 
suggestions on the ways and means for at- 
taining and maintaining correct alignment. 



FUNDAMENTALS OF GOOD GEAR OPERATIONS 




no 



GEAR DRIVES 






Since vibration tends to loosen bolts and 
nuts, they should be inspected periodically 
and tightened whenever necessary. 

Alignment 

Accurate alignment of gear drives is most 
important. Misalignment develops unusual 
stresses and overloads. Excessive wear on the 
coupling is a positive indication of misalign- 
ment. 

A flexible type coupling, rather than a rigid 
one, should be used between the prime mover 
and the reducer in direct drives. Transmission 
chains and belting are also used for trans- 
mitting the mechanical power between the 
driver and the reducer or the gearing and 
the driven unit. 

Secure mounting on a rigid foundation is 
essential to proper alignment. Another aid to 
maintaining alignment is a bed or base plate 
for the support of both the motor and reducer. 
These can be supplied by the manufacturer 
of the gearing or be constructed locally. 

Even when bed plates are supplied, care 
should be taken in setting up the installation. 

One easy way to level up the bed plates is 
to use small steel plates which can be shimmed 
up with thin pieces of metal. 

Coupling alignment can be checked with 
a leaf gage and a straight edge. 

Lubrication 

Standard lubrication practices are quoted 
later in this chapter. These standards are 
issued by the American 'Gear Manufacturers 



Association and have been agreed upon and 
accepted by the members of the association. 

Suppliers of lubricants can furnish suitable, 
high-quality, industrial grades of mineral oils 
to meet the different requirements set forth. 
Some refiners, incidentally, are offering syn- 
thetic oils for enclosed gear units, and these 
products may warrant listing as lubricants 
by the association in the near future. 

It is always advisable to seek and follow the 
recommendations of the manufacturers of the 
gear equipment regarding lubrication, espe- 
cially where operating conditions are special 
or unusual. 

For instance, some makers of gear drives 
may recommend that the initial oil be drained 
and filtered or replaced with new oil at the 
end of one week or ten days, or after 30 days 
under some circumstances, rather than at the 
end of two weeks. 

Changes of oil every six months thereafter, 
or three months if circumstances warrant it, 
represent good practices. Under exceptionally 
wet or moisty conditions, replacement every 
one to three months may be called for. 

Lubrication may be by the splash method or 
by means of a force-feed system. 

Splash lubricated units are commonly pro- 
vided with filter and drain plugs and oil level 
plugs, pet cocks or other oil level gages. 

Fill the oil well or reservoir up to the proper 
indicated level only. Do not fill with oil higher 
than the correct level mark and never com- 
pletely fill the case or housing. 



METHODS OF AU6NI.N0 



TIN OR 
SHUT 
IRON 




FOUNOAT/ON 



11 



PLANT MAINTENANCE MANUAL 





On the other hand, do not allow the en- 
closed gear unit to run clry. 

Inspect the oil level regularly and replenish 
the oil supply whenever necessary. 

In force feed installations check the opera- 
tion of the system periodically and clean and 
flush the filters periodically. 

Oil Temperature 

When very high oil temperatures prevail, 
the trouble may be caused by a continuous 
overload because the unit originally selected 
was too small. 

Another overload condition may occur 
where a larger motor than the one originally 
contemplated has been used. The situation 
can arise where a larger motor has been 
installed to handle an increased load without 
a corresponding change of the reducer. 

Too much oil in the casing causes churn- 
ing which also results in overheating. 

Enclosed gear drives running continuously 
tend to operate at a somewhat higher tem- 
perature than when running intermittently. 

If a speed reducer— which has been prop- 
erly installed and lubricated and not over- 
loaded—is otherwise performing satisfactorily, 
there is little cause for concern if it runs quite 
hot as long as the temperature does not con- 
tinue to rise. Taking an oil temperature read- 
ing occasionally will provide a check on that 
point. 

Standby and Storage 

When speed reducers are used to operate 
standby equipment, they should be operated, 
say, once a month in order to insure that the 
equipment will perform satisfactorily when 
needed. 

If to be stored away, enclosed gear drives 
should be drained of oil and cleaned and a 
rust preventive applied to the gears and bear- 
ings. 

Then when taken out of storage for use, 
the gear unit should be cleaned out and 
filled to the proper level with oil before plac- 
ing back in service. 




LUBRICATION OF ENCLOSED AND 
OPEN GEARING 

The standard specifications,* given on this 
and the following pages, cover the methods 
of lubricating and the types and grades of 
oil to be used in enclosed gear drives and 
open gearing. They are applicable to the 
following types of gearing: helical, straight 
bevel, worm, spur, herringbone, spiral bevel, 
and hypoid. 

These specifications apply only when the 
gears are designed and rated in accordance 
with AGMA standards. The ambient tempera- 
ture range for which they apply is from to 
150 deg F. Gear drives operating outside of 
this range or those operating in extremely 
humid or chemical-laden atmospheres shoute 
be referred to the gear manufacturer or lu- 
bricant supplier for his recommendation. 

Lubrication of Gear Teeth 

The areas of contact on gear teeth are 
relatively small and the unit pressures pro- 
duced in transmitting the loads are relatively 
high. It is therefore essential to provide a 
film of lubricant of sufficient strength to with- 
stand the localized pressure during the period 
of contact. The peripheral speed of the gears 
governs the period of tooth contact and de- 
termines the length of time the film must with- 
stand the pressures. When speeds are high, 
the time is very short and the loads are usually 
light and as a result an oil of comparatively 
low viscosity should be used. When speeds 
are low and the loads heavy, the contact time 
is considerably longer and an oil of higher 
viscosity should be used. 

Temperature 

The ambient temperature, which is here 
defined as the temperature of the air in the 

*This "AGMA Standard Specification" for the 
Lubrication of Enclosed and Open Gearing 
was approved as a Standard in June 1946 by 
the American Gear Manufacturers Association. 



112 



GEAR DRIVES 





vicinity of the gears or gear unit, has con- 
siderable bearing on the viscosity of oil to 
be used. In general, the viscosity of mineral 
oil varies inversely with the temperature, 
which fact makes it desirable to use an oil of 
heavier grade at high ambient temperatures 
than would be used for the same application 
operating in a low ambient temperature. Also, 
for low temperatures an oil must be selected 
which has a pour point lower than the mini- 
mum temperature expected for the application. 

Where the operating temperature for any 
one application varies more than 80 deg F., 



a viscosity index (Dean and Davis) of 60 mini- 
mum is desirable. For ordinary applications, 
a viscosity index of 20 minimum is satisfactory. 
Type of Oil 
Lubricating oils for use with gears and gear 
units should be high grade, high quality, well 
refined petroleum oils. They must not be cor- 
rosive to gears, or to ball, roller or sleeve 
bearings; they must be neutral in reaction; 
free from grit or abrasives; and have good 
defoaming properties. For high operating tem- 
peratures they must have good resistance to 
oxidation. 



TABLE I - VISCOSITY RANGE FOR VARIOUS 
AGMA LUBRICANTS 



AGMA Lubricant 
No. 

1 


Viscosity Range 
At 100 deg F. 


SUV. Seconds 
At 210 deg F. 


180 to 240 





2 


280 to 360 





3 


490 to 700 





4 


700 to 1 ,000 





5 





80 to 105 


6 





105 to 125 


7 





125 to 150 


7 Comp.* 





125 to 150 


8 





150 to 190 


8 Comp.* 





150 to 190 


9 





350 to 550 


10 





900 to 1 ,200 


11 





1,800 to 2,500 



'The oils marked "Comp." are those compounded with 3 to 10 per 
rent of acidless tollow or other suitable animal fat. 

Oils No. 9. 10 ond 11 should b* of a tacky adhesive nature so that 
they will adhere well to the tooth surfaces. 



113 



PLANT MAINTENANCE MANUAL 



Lubricants of the straight mineral type are 
to be used for all except worm and hypoid 
gears. For worm gears, additions of 3 per 
cent to 10 per cent of acidless tallow or 
similar animal fats are desirable. For hypoid 
gears, an acceptaole grade of extreme pres- 
sure lubricant is recommended. For applica- 
tions where loads, speeds or temperatures are 
abnormal, it may be necessary to use oils 
with special additives. 

OIL LUBRICATION OF ENCLOSED 
GEAR UNITS 

The recommendations in this section cover 
the lubrication of enclosed gear units of all 
types within the range of sizes of commercial 
enclosed gear drives. 

Limitations 

They are applicable to enclosed gear drives 
in which the high-speed shaft rotates within a 
nominal speed range of 600 to 1,800 rpm. 
One exception to this is high-speed gear units 
which normally operate at speeds higher than 



1,800 rpm. The recommendations for these 
are shown in Table II. 

For spur, helical and herringbone gearing, 
the recommendations as shown apply only 
to gears cut after heat-treatment. If they are 
heat-treated after cutting, the next higher 
AGMA lubricant number is to be used for a 
given unit size and ambient temperature. 

The recommendations as shown for units 
using straight or spiral bevel gears are for 
gears heat-treated either before or after 
cutting. 

Maintenance 

To obtain long life from a gear unit, it is 
necessary that the oil be clean and free from 
sludge at all times. To be assured of this, the 
oil must be changed at regular intervals. 

For a new unit the oil should be drained 
at the end of two weeks of operation and the 
case thoroughly flushed with light flushing 
oil. For refilling, the original oil can be used 
if it has been filtered, otherwise new oil must 
be used. After this, a change of oil every 



TABLE II - RECOMMENDED LUBRICANTS FOR ENCLOSED 
UNITS OF ALL TYPES EXCEPT WORM GEARS 



Types of 
Units 


Size of 
Units 


Ambient Temperature, 
deg F. 


O-40 

use 

AGMA 

No. 


41-100 

use 
AGMA 

No. 


101-150 

use 
AGMA 

No. 


Parallel 
shaft 
units 


Low-speed, Centers 

up to 20 in. 
Low-speed, Centers 

over 20 in. 


2 
3 


4 
5 


5 
6 


Planetary 
gear 
units 


O. D. of housing 
up to 16 in. 

O. D. of housing 
over 16 in. 


2 
3 


3 

4 


4 
5 


Gearmotors 


All sizes 


2 


4 


5 


Spiral or 
straight 
bevel 
gear 
units 


Cone distance 
up to 12 in. 

Cone distance 
over 1 2 in. 


2 
3 


4 
5 


5 
6 


High-speed 
units 


All sizes 


1 


2 


3 



114 



GEAR DRIVES 



2,500 hr of operation or every six months, 
whichever occurs first, is sufficient for units 
operating under normal conditions. Where 
operating conditions are severe, such as a 
rapid rise and fall in temperature of the gear 
case with accompanied sweating of the inside 
wall and resulting formation of sludge, or 
where operation is in moist or dusty atmos- 
pheres or in the presence of chemical fumes, 
it may be necessary to change the oil at in- 
tervals of one to three months. 

Sludge in gear units may be caused by 
metallic particles ground off the gears, from 
dust and dirt and by the presence of mois- 
ture or chemical fumes. Therefore, every 
precaution should be taken to prevent water 
and foreign particles from entering the gear 
case. 

OIL LUBRICATION OF OPEN GEARS 

The recommendations in this section cover 
the lubrication of open and semi-enclosed 
gearing of all types. 

They are applicable to gears operating at 
moderate and slow speeds. The maximum per- 
missible speed is that at which the lubricant 
will adhere to the teeth and will van/ with 



the application and the^operating conditions. 
This part covers oil lubricanon of gears as 
distinguished from grease lubrication. The oil 
used may, however, contain special additives 
to increase adhesiveness. 

Methods of Lubrication 

Various methods have been devised for the 
lubrication of open gearing because of the 
wide range of applications in which they are 
used. These methods can, however, be 
grouped in two general classes which are as 
follows: 

(A) Slush-Pan Lubrication 

This method of lubrication is recommended 
for high grade heavily loaded gears operat- 
ing at moderate and slow speeds. It involves 
the use of a slush pan mounted below one 
of the gear elements in a position such that 
a number of gear teeth are submerged in oil. 
As the gear rotates, a small amount of lubri- 
cant clings to the teeth and is carried into 
the mesh. 

The oil used should be of a tacky nature 
so that it adheres well to the tooth surfaces. 
It should be heavy-bodied but not so heavy 
as to channel in the pan. 



TABLE III- RECOMMENDED LUBRICANTS FOR 
ENCLOSED WORM GEAR UNITS ONLY 



Service and Worm Speed 


Ambient Temperature, 
deg F 


O-40 

use 

AGMA 

No. 


41-90 

use 
AGMA 

No. 


91-120 

use 
AGMA 

No. 


Intermittent operation 
* All worm speeds 


5 


5 


7 Comp. 


Continuous Operation 
Worm speeds below 
600 rpm. 


7 Comp. 
♦♦Diluted 


8 Comp. 


8 Comp. 


Continuous Operation 
Worm speed 600 rpm. 
and over 


7 Comp. 
♦♦Diluted 


7 Comp. 


8 Comp. 



* Where period of operation is insufficient to produce any appreciable 
rise in oil bath temperature. 
** Diluted AGMA No. 7 Comp. oil should be diluted with a lighter oil, pre- 
ferably not exceeding 500 sec. viscosity at 100° F. until the desired 
fluidity is obtained. The lubricant used for dilution should be of the 
same basic crude as that of the recommended oil. The lubricant sup- 
plier should be consulted if there is any doubt. 



115 



PLANT MAINTENANCE MANUAL 



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Wear practically ceases after a "running in" pe- 
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factured, and operated. 


Not detrimental, if gradual and unless it goes 
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When unpitted areas of teeth can no longer 
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116 



GEAR DRIVES 



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117 



PLANT MAINTENANCE MANUAL 



(B) Hand Lubrication 

Hot— by brush or pouring 
On applications where a slush pan is im- 
practical, this method of lubrication is rec- 
ommended for moderate speeds and heavy 
loads or when gears are operating at ele- 
vated temperatures. It consists of heating the 
lubricant to a temperature such that it flows 
freely and is then applied to the gears with 
a brush or by pouring. An extremely adhesive 
lubricant should be used. 

Cold— by brush or pouring 
This method of lubrication is recommended 
only for slowly moving and roughly cut or 
cast teeth carrying comparatively light loads. 
It consists of applying the lubricant to the 
gears with either a brush or paddle. The oil 
used should be adhesive in nature so it will 
stay on the teeth. 

Hand-Oiled 
This type of lubrication is limited to small 
gears which are used principally for motion 
transmission where the loads are very light. 
The oil is applied by merely pouring on the 
gear teeth. 



Maintenance 

Because open gearing comprises so many 
types and is used under such a wide range 
of operating conditions, it is difficult to make 
recommendations applicable to all situations. 
Often such gears are protected by dust- 
excluding sheet metal housings while others 
have no covering. 

For slush-pan lubrication, the oil shoiHd be 
changed once every six months for applica- 
tions where it is not subject to dust or con- 
tamination. Where dust or an excessive 
amount of moisture is present, the oil should 
be changed every two to four months. 

All hand-lubricated gearing depends on 
the periodic application of oil to the gears to 
maintain a constant film. The frequency of 
application depends on speed, load, and 
operating condition and may vary from one 
hour where speeds and loads are high to 24 
hours for lightly loaded slow-'speed drives. 
The proper intervals between applications can 
be determined only by inspection of the tooth 
surfaces. 

Gears operating in dusty atmospheres 
should be periodically cleaned with kerosene 



TABLE IV - RECOMMENDED LUBRICANTS FOR 
OPEN GEARING OF ALL TYPES EXCEPT WORM GEARS 



Method 


Ambient Temperature, deg P. 


0-40 41-100 101-150 
use use use 
AGMANo. -AGMANo. AGMA No. 


Slush pan 


3 


5 


6 


Hot — by brush 
or paddle 


10 


10 


11 


Cold — by brush 
or paddle 


6 


8 


10 


Hand-oiled 


4 


6 


8 



TABLE V - RECOMMENDED LUBRICANTS FOR OPEN WORM GEARS ONLY 



Method 


Ambient Temperature, deg F. 


0-40 

use 

AGMA No. 


41-100 

use 

AGMA No. 


101-150 

use 

AGMA No. 


Cold or hot — 
by brush 
or paddle 


6 


8 


- 



118 



GEAR DRIVES 



or other suitable solvent. Ihe dirt and grit 
adhering to them can seriously damage the 
tooth surfaces if it continuously passes through 
the mesh. 

GEAR TOOTH WEAR AND FAILURE 

Gear tooth wear and failure in operation 
may result from the following conditions: 

a. Incorrect center distances resulting in in- 
sufficient root clearance and backlash. 

b. Misalignment; excessive shaft deflection,- 
defective related parts, worn bearing, etc. 

c. Incorrect or insufficient lubrication. 

d. Foreign matter in lubricant and between 
teeth, such as abrasive dirt or particles of 
metal worn from teeth. 

e. Excessive temperatures. 

f. Excessive loads, or shock loads. 



g. Vibration. 

h. Excessive speeds. 

i. General abuse. 

To avoid misunderstanding regarding the 
terms used to explain the different types of 
wear and failure in gearing, the American 
Gear Manufacturers Association has issued 
the Standard Nomenclature which is pre- 
sented in table form. 

In many cases there is a marked similarity 
which may be a matter of degree or rough- 
ness, such as abrasion and scratching. Fur- 
thermore, some kinds of wear may be of a 
minor nature at the start, but if the wear con- 
tinues, more severe conditions may occur. An 
example of this is scoring which may lead to 
galling, seizing and welding, if the conditions 
causing the wear become serious. 



19 




CHAPTER 12 



PLAIN BEARINGS 



Some part, or parts, of practically every 
machine, engine or other like mechanism 
moves— revolves, oscillates or reciprocates. 
These countless moving parts are supported 
by bearings. 

Plain bearings are those in which the con- 
tacting surfaces revolve or slide with respect 
to each other. These bearings are, therefore, 
either of a radial or guiding type, depending 
upon the motion. The former is commonly 
called a journal bearing because a journal 
or shaft revolves in a sleeve, box, casing or 
other housing of some sort. The second type 
is called a guide bearing. 

Another basic form of bearings is that in 
which balls or rollers separate the moving 
surfaces. Bearings of this sort are covered in 
another chapter. 

The so-called plain bearings, of which this 
chapter treats, are made of certain metals and 
other materials which have good bearing 
qualities. They may be solid, split or two-part, 
or quarter-box or four-part. Some bearings 
are also flanged in various ways. 

One of the more common forms of these 
bearings is the sleeve type. The entire sleeve, 
for instance, may be made of one high-grade 
bearing metal throughout. Or it may be made 
up of a bearing-metal lining sweated or 
bonded to a metal backing or a shell of an- 
other metal or material. Bushings perform 



much the same functions as sleeve bearings 
and are usually made of the same bearing 
metal throughout. 

As is well known, friction is "the resistance 
to motion of two surfaces in contact with 
each other." Lubrication of some sort or an- 
other reduces friction. Modern lubrication 
practices have made possible the present-day 
high efficiencies of plain bearings— efficien- 
cies as high as 96 to 98 per cent. 

BEARING MATERIALS 

No one kind of bearing material is suitable 
for use in any and all applications. There are, 
therefore, a variety of bearing metals and 
materials and each has its own particular 
usefulness. 

In all cases the use of the right bearings 
for the job to be done is essential to good 
bearing performance. So it is advisable to 
consult with the manufacturers of bearings for 
their experienced recommendations. 

Although most bearings are of metal, other 
materials such as wood, rawhide, fibres and 
plastics are also used. The metals are chiefly 
alloys with bases of copper, tin, lead or cad- 
mium in various combinations with each other 
and with other metals. Good bearing metals 
have the quality of retaining lubricants in the 
working surfaces. 



120 



PLAIN BEARINGS 



Copper Base Alloys 

Copper base alloys are widely used for 
bearings. Representative of commercial cast 
copper base alloys are the following SAE 
classifications of high lead tin bronzes: 

NOMINAL 



ponent of the copper bronzes, and is found 
in the tin-base alloys as well. Another type 
of lead bearing alloy has a base of 97 to 
98% lead, with small amounts of other metals 
making up the balance. 



COPPER TIN LEAD ZINC 


SAE 64 Phosphor Bronze 


80 


10 


10 




SAE 660 Bronze Bearing 


83 


7 


7 


3 


SAE 66 Bronze Bearing 


85 


5 


9 


1 


High Lead Bronze 


70 


5 


25 





These alloys are by no means the only ones 
used. In fact, variations of 1 or 2% above or 
below the nominal values given are quite 
standard. There are also phosphor bronze 
metals that combine certain of the features 
of these grades. Another cast bronze alloy 
contains no tin. 

Typical of the tin bronzes are the SAE 62, 
63 and 65 alloys which have 88 or 89% 
copper and 10 or 11% tin. The first two also 
have some 2% of zinc or lead, respectively. 

Babbitt Metals 

The babbitts or babbitt metals are the gen- 
eral terms applied to white metal bearing 
alloys. They include both the soft lead and 
the tin-base alloys and are used as liners in 
bronze or steel backings. The babbitts are 
considered below according to whether they 
are tin base or lead base, since the base 
element is the one by which they are usually 
classed and considered. 

Tin Base Alloys 

The tin-base babbitts contain principally 
tin, copper, antimony and lead in differing 
proportions. In the SAE Babbitts 10, 110 and 
11, for instance, the tin ranges from 90 to 
86% and the lead component is about y$ 
of 1%. 

Another grade of tin babbitt contains some 
60% of tin and about 25% of lead. There 
are, of course, alloys with other variations 
of these percentages. Cadmium up to 1%, 
nickel and silver are sometimes added. 

Lead Base Alloys 

The lead-tin-antimony alloys are also im- 
portant bearing metals. The high-lead bab- 
bitts like the SAE 13 and 14, for example, 
contain from 85%, and even more, to 75% 
lead. The tin and antimony run from approxi- 
mately 4 to 10% and 9 to 16%, respectively. 
Alloys containing as high as 90% lead and 
as low as 63% lead are also used. 

As already noted, lead is a regular corn- 



Cadmium Base Alloys 

Cadmium-silver-copper alloys have a very 
high percentage of cadmium, as high as 98% 
and more. These alloys are used for linings 
which are backed with steel. 



7 PROPERTIES OF GOOD BEARING 

MATERIALS 
Load Carrying Strength 
Low Coefficient of Friction 
High Thermal Conductivity 
Quick Assembly 
Easy Replacement 
Durability 
Corrosion Resistance 



Copper-Lead Bearings 

Copper-lead alloys are also employed as 
automotive engine bearings. Standard bear- 
ings of this composition carry from 75 to 55% 
copper and from 23 to 45% lead. 

Plastic and Other Bearing Materials 

Among the plastic bearings are those of a 
Micarta fabric base for roll necks in steel 
mill operations and Bakelite molding plastic 
bearings containing graphited oils used in 
textile cloth rolls. Carbon materials are also 
employed for bearings. Hardwood bearings 
impregnated with high grade oils provide 
self-lubricating bearings for food, textile, 
paper and other machinery. 

Self-Lubricating Bearings 

Graphited bearings are a self-lubricating 
bearing. They may be used where lubrication 



121 



PLANT MAINTENANCE MANUAL 




is difficult or is likely to be neglected or where 
ordinary lubricants may damage the goods 
being processed. Graphite bearings may be 
formed by grooving or drilling bronze bear- 
ings and inserting graphite in the grooves or 
holes in such a way that the graphite holds 
its place permanently. 

Another kind of self-lubricating bearing is 
the porous bearing which is made by pressing 
and sintering, for instance, powdered mixtures 
of copper, tin, lead and graphite into a por- 
ous structure to the degree of porosity desired. 
Oil is impregnated into the pores of the bear- 
ing to provide the necessary lubrication. 

According to SAE typing, sintered metal 
powder bearings are either of a bronze base 
or an iron base. There are two classes of 
each— copper-tin and copper-1ead-tin for the 
former and iron-carbon and iron-copper for 
the latter. 

PREVENTIVE MAINTENANCE 

Satisfactory operations and long life result 
when bearings are properly designed, the 
bearing materials and finish are good, align- 
ment is right, proper clearances are provided 
and periodic maintenance attention is given 
to them and their lubrication. 

Neglect of bearings is the cause of most 
bearing failures. Another is improper fit. 
Shielding bearings helps to keep out dirt and 
foreign matter. 

Bearings should be inspected frequently 
and at regular intervals. Inspect them for 
ridges and scoring; check for sufficient thick- 
ness of the bearing metal. Examine both bear- 
ings and journals or shafts for wear. Badly 
worn bearings should be replaced because 
they cause vibration and excessive wear on 
other moving parts of the machine. 

Draining and cleaning bearings from time 
to time usually pays dividends in the dollars 
saved by low cost maintenance. In wiping 
bearings and in cleaning oil pockets, use 
rags or toweling-not cotton waste. 

Bearing Clearances 

Proper bearing clearance is most important. 
The inside diameter of a bearing should be 
slightly larger than the diameter of the shaft 
or journal for best operation and proper lu- 
brication. This clearance depends primarily 
upon the size or diameter of the bearing. 

If the clearance is too close, oil flow is 
restricted and overheating may result. If the 
clearance is too great, the oil may leak out 
at the ends of the bearings. 

This condition can lead to insufficient oil 
in the pressure area. 



22 



PLAIN BEARINGS 



Generally speaking, the larger the bearing, 
the heavier should be the body of the lubri- 
cant. The vital role that the use of the right 
lubricants plays in bearing operation and 
good lubricating practices is discussed else- 
where in this chapter. 

Bearing Adjustment 

An/ adjustments found necessary are simple 
and are mainly those of alignment and fitting. 

Care should be observed, therefore, in 
aligning and fitting bearings to an installation. 
This point is particularly important where a 
line of shafting, for instance, is supported by 
several bearings. 

Sometimes shims are used for making ad- 
justments, particularly for the improvement of 
clearance. In split bearings which were made 
by casting as a whole and then cut in halves, 
for instance, shims are often inserted at the 
parting faces to make up for the material cut 
out and thus restore the bearing to the origi- 
nal cylindrical size. 

Shims may also be employed to compensate 
for shaft or bearing wear. Usually, however, 
it is better to replace worn bearings rather 
than "jack" them up with shims. Besides, it 
is often easier to make a complete replace- 
ment than to make the necessary adjustment. 

Bearing Temperatures 

Most bearings operate at medium tempera- 
tures ranging usually from 90 degrees to 120 
or 140 degrees F. If operating conditions are 
such that temperatures go considerably below 
the lower figure given above, special low- 
cold-test oils should be used to prevent con- 



gealing and difficulties in feeding lubricants 
If bearings heat to temperatures greatly in 
excess of the top figure given, an investiga- 
tion should be made to determine the cause. 
Such heating may arise because of bad op- 
erating conditions, because of the use of a 
lubricant unsuitable in quality or because the 
oil is insufficient in quantity. This dangerous 
heating situation should be corrected. 

If both the operating conditions and the 
quality of oil used are good, the solution to 
the heating problem may be the introduction 
of some other means of oil circulation. 

Many bearings can run much hotter than 
thought feasible. Heating up to a tempera- 
ture uncomfortable to the touch is not, in 
itself, an indication of trouble if it takes an 
hour or more to do so. A real danger signal, 
however, is a rapid heating up in, say, 10 to 
15 minutes. 

Pouring Babbitt Bearings 

There are several ways of pouring babbitt 
bearings, so it is always well to consult the 
manufacturer for his recommendations. 

In any case, the following practices with 
regard to casting and pouring bearings will 
help to insure good bearings securely lined to 
the backing. 

One important point is to use only new bab- 
bitt of the right grade. Do not mix reclaimed 
or scrap metal with new. 

Also be sure to melt enough metal to pour 
the entire bearing so that uniform results will 
be obtained. Heat the babbitt to the tempera- 
ure recommended by the manufacturer— a rep- 
resentative range is from 700 to 950 deg F— 



MAINTENANCE PRACTICES WORTH REMEMBERING 



7 . Inspect bearings periodically. 

a. Constantly operated bearings should be in- 

spected every day. 

b. Where operations are not so constant, in- 

spect at least once a week. 

2. Check bearings for perfect alignment. 

3. Replace all worn bearings before they fail. 

4. Lubricate bearings according to a regular plan, 

always using the right type and grade of clean 
lubricant recommended by the manufacturer. 

5. Make sure bearings and surroundings are clean 

at all times. Cleanliness insures greater bear- 
ing efficiency and longer life with less main- 
tenance. Foreign matter, especially of a gritty 
or abrasive nature, damages bearings 



123 



PLANT MAINTENANCE MANUAL 




so that the metal will pour like water. A 
rough test is tQ insert a pine splinter in the 
melting pot. If the stick chars, the temperature 
is right. Some authorities say that the splinter 
should flame up. 

Make sure that the shell is thoroughly clean 
and dry, using a wire brush and a blow torch, 
if necessary to drive out moisture. Follow this 
precaution carefully because the presence of 
moisture may cause burns and other accidents. 

Warm the shell to 200 to 212 deg F before 
pouring. Pour the molten metal as fast as 
possible. Make sure that all the space beween 
the shell and the mandrel is filled. In fact, 
overfill, to allow for shrinkage of the metal 
when it cools. If the bearing is poured in a 
vertical position, one way to provide over- 
fill space is to build up a waste head at the 
top end. 

Rebabbitting 

When inspections show that the old metal 
is rough and uneven and that there is in- 
sufficient metal, the lining should be removed 
by melting it out and a new lining poured in. 
Only experienced personnel should be al- 
lowed to rebabbitt bearings. 

The first step to take is to make a sketch 
of the grooving, beveling or crowning so that 
these features may be duplicated in the new 
bearing. 

Heat the bearing to some 20 deg F above 
the melting point of the bearing metal. A 
clean coke fire or a blow torch may be used. 
Be sure that no moisture is present. 

Clean out all recesses and wash with suit- 
able cleaning materials. Stop up oil and drain 
holes with plugs. Be sure that the holes are 
opened up again after rebabbitting. 

Tinning— the application of a thin bonding 
coat of solder or tin— usually helps the bab- 
bitt to fuse or stick to the shell. 

Pouring steps and processes have already 
been described. 

Fitting or Scraping 

One way to tell whether scraping is nec- 
essary, in a split bearing for instance, is to 
coat the journal with lamp black and oil or 
either red or black lead with oil, or Prussian 
blue. Then rotate the shaft back and forth 
in half of the bearing. Spots where the coat- 
ing adheres to the bearing should be scraped. 
Do this until the spots are so distributed as 
to indicate a suitable bearing surface contact 
with the journal. 

Repeat this process with a complete bear- 
ing properly positioned on the journal. 

When necessary to scrape a bearing for 



124 



PLAIN BEARINGS 



fitting to the journal, use care to keep the 
lining concentric with the shell. 

Approved bearing fitting compounds may 
be used. Be sure to remove all traces of the 
compound by cleaning and flushing the bear- 
ing with a suitable solvent. Keep the com- 
pound out of the lubricating system. 

Add Life To Your Bearings by Observing 
These Simple Rules 

Never neglect a bearing because it is out 
of the way. 

Don't wait until a bearing smokes before 
attending to it. 

Make sure that oil holes are open and not 
clogged with dirt. 

Investigate a bearing when it heats up 
rapidly say in 10 or 15 minutes instead of 
taking an hour or more. 

Never use an engine or machine which is 
known to have bearings in poor shape. In 
an engine, for instance, defective bearings 
may cause loss of oil, low pressure and high 
consumption of oil, missing and knocking of 
engine and sluggish performance. 

LUBRICATION 

The fluid film theory of lubrication explains 
the reason for the high bearing efficiencies 
possible today. 

Because the oil adheres to the shaft and 
bearing and because it is dragged along 
when the shaft or journal rotates, the oil 
forms a wedge-shaped film between the 
journal and the bearing. The film separates 
the shaft from the bearing so that there is no 
metal J to-metal contact and the pressure set 
up in the oil film supports the load on the 
bearing. 



When the shaft or journal is at rest on the 
bottom of the bearing, there is no oil wedge 
in the pressure area since the oil has been 
squeezed out by the weight of the shaft at 
rest. When the journal starts to turn, counter- 
clockwise for instance, the friction causes the 
shaft to "back up" the left side of the bear- 
ing. The oil then flows into the area along 
the bottom where the shaft formerly rested. 
The weight of the shaft tends to make it drop 
back to its former position at the bottom 
of the bearing. In doing so, the journal en- 
counters the oil film which lifts the shaft away 
from the bearing at the pressure area. The 
rotation of the journal keeps drawing the oil 
into the pressure area. 

Any friction now takes the place in the oi! 
film and becomes a fluid friction. 

These oil films are in reality very thin- 
being onlv a few thousandths, or even ten- 
thousandths, of an inch thick. 

Proper clearance between the bearing and 
the journal or shaft is important to good lu- 
brication, as has been explained before. Op- 
erating conditions which affect the kind of 
lubricant to be used are the speeds of shaft 
rotation and bearing pressures and tempera- 
tures. In general, the slower the speed of 
rotation, the heavier the body of the oil; 
and in some such cases grease may be pre- 
ferred. A lighter bodied oil should be used 
if the journal speeds are high. Bearings that 
operate at very high speeds should be lubri- 
cated with very light oils. 

The influence of pressure on the grade of 
lubricant to be used is also considerable. For 
heavy pressures at low speed, a heavy lubri- 
cant should be used. Especially in those cases 



SIZE OF BEARING 

SPEED OF OPERATION 
TEMPERATURE, ROOM 

PRESSURE 

BEARING CONDITION 




PLANT MAINTENANCE MANUAL 



where speeds are low, metal-to-metal contact 
of the rubbing surfaces is a factor to watch 
closely. It may be that solid or semi-solid 
lubricants should be employed. 

Methods of applying oil are given later. 

Oil Distribution 

Where desirable for the even distribution 
of oil, bearings may be grooved in various 
ways. Grooving depends to a large extent 
upon the lubrication system used. 

In some cases a single horizontal groove 
running lengthwise of the bearing is sufficient. 
In other instances, more extensive grooving 
may be desirable for distributing the oil to 
the pressure area or for guiding it to other 
sections. 

Grooves should not be located in the actual 
pressure areas,- neither should they be cut too 
close to the bearing edges. Grooves should 
be shallow and the edges should be rounded 
off to prevent scraping. 

Oil should be applied at that part of the 
bearing where the surface pressure is at a 
minimum. 

The main purpose of any groove is to dis- 
tribute the oil in a way that will form and 
maintain the fluid film between the bearing 
and the journal. 

Various types of grooves are illustrated. 

Grease 

Grease is also used as a lubricant in cer- 
tain installations where the formation and 
maintenance of an oil film would be difficult 
or impossible. Representative applications are 
where shafts operate at slow speeds and 
loads are heavy and where operating tem- 
peratures are high. Soda greases and lime 
greases are the general types of greases 
used. 

T his form of lubrication may be advantage- 
ous in operations that are intermittent and 
where it is hard to retain oil in the system or 
supply the system with a uniform feeding of 
oil. In some cases where hand oiling is prac- 
ticed—and neglected— the use of a grease may 
provide more reliable service. 

Since greases do not flow as easily as oil, 
greases should be applied closer to the bear- 
ing pressure area. Grooving, therefore, should 
be wider than for oil and be so arranged 
that the correct distribution of grease is as- 
sured. Common forms of grooves are the 
Figure 8 and the X types. 

Methods of feeding grease are by direct 
application to the journal; gravity feed grease 
cups; compression cups in which pressure is 
created by turning the cover cap by hand, 




a spring or compressed air. Mechanically 
operated lubricators and grease baths are 
also used. 

Solid Lubricants 

Solid lubricants, which are also used in 
bearings, should be able to adhere to the 
metal and produce a smooth surface. One 
of the most common lubricants of this sort is 
graphite which has these necessary qualities. 

Solid lubricants are applied either dry or 
by mixing with semi-solid or liquid lubricants. 
Oilless graphited bearings already referred 
to come in this classification. They may be a 
metal alloy or wood mixed or impregnated 
with graphite talc or other solid lubricant. Or 
the graphite may be set in grooves or spots. 

Water Lubrication 

Water is also used as a lubricant in roll 
neck bearings made of fabric treated with a 
plastic with a mineral filer and molded into 
a bearing. These bearings are used in rolling 
mill operations in which pressures are high. 

The injection of oil or grease is advisable 
to overcome friction in starting up the rolls 
after they have been stopped for a while. The 
application of oil or grease is also recom- 
mended when the machinery is to be shut 
down for an extensive period. 



126 



PLAIN BEARINGS 




Water is also a partial lubricant and cool- 
ant in lignum-'vitae bearings which are com- 
monly used in underwater service. Applica- 
tions of hard wood bearings are in stern 
tubes of ships. Additional lubrication with oil 
or grease is also usually provided. 

OILING SYSTEMS 

The proper application of lubricants is 
important to the best operation of bearings 
and for the reduction of friction and wear. 
There are several methods of oiling— hand, 
cup, drip feed, splash, slinger, pressure, etc. 
Oil circulating systems are of two kinds, 
gravity feed and force feed. 

Hand oiling is the least efficient method of 
lubricating a bearing. It is sometimes used 
where shafting speed is slow and in other 
low-speed applications. Its unsatisfactory fea- 
ture is that the distribution of oil is very un- 
even, to say the least. At the time of oiling 
the supply is excessive, but the excess is soon 
dissipated and the bearing may have little 
or no lubricant until the next oiling. 

Cup Oilers and Drop Feeds 

There are several arrangements for cup oil- 
ing. The devices may be bottle, wick or 
siphon oilers, or drop feed cups. Systems of 
this sort are more reliable than hand oiling. 



Bottle oilers carry the lubricant in a glass 
or plastic reservoir and transfer the lubricant 
to the journal by a metal spindle which 
touches the shaft journal. The flow of oil is 
caused by the vibration set up in the spindle 
by the rotating shaft. Changes in tempera- 
ture, however, affect the rate of oil flow be- 
cause the close clearance between the spindle 
and its tight fitting sleeve. 

Wick feed cups carry a uniform supply of 
oil from the reservoir to the bearing by ca- 
pillary action of the wick which is dipped in 
the cup. The number of strands and the wick- 
ing material regulate the rate of feed. 

There are several variations of wick-packed 
bearings which have been used extensively 
in car journals. The oil soaked waste touches 
the journal directly or by way of a wick. 

Drop feed oilers supply a fairly regular 
amount of lubricant, the flow of which is regu- 
lated by a needle valve. Temperatures and 
viscosities affect the rate of oil feed. Sight 
glasses make the oil drip visible. 

Slinger Type Oiling 

In the dip-and-sling type oiling systems, a 
ring, chain, collar or disc carries the oil from 
the reservoir to the bearing. In a ring oiled 
bearing, for instance, a ring rides on the top 
of the journal. As the shaft revolves, the ring 
also rotates, lifting oil from the reservoir to 
the bearing. 

The actions of chain and disc oilers are 
quite similar except that in the disc or collar 
type, the disc is attached -to the shaft. The 
disc picks up oil from the reservoir through 
which it passes and slings it to the parts that 
need it. 

Splash and Bath Lubrication 

In splash lubrication, the bearing dips into 
an oil bath and splashes oil into the parts 
that need continuous lubricating. This system 
is used for bearings where they are enclosed 
in an oil-tight housing, as in crank cases of 
engines, compressors, etc. 

Bath oiling differs in that the entire bearing 
surfaces are submerged in an oil bath. This 
method finds its chief application in vertical 
bearings such as those of the thrust type and 
those used in hydraulic turbines and in some 
textile machines. 

Circulating Systems 

Oil circulating systems ore automatic cen- 
tralized set-ups that provide a constant lu- 
brication to the various bearings of an in- 
stallation. Circulating oil flows back into the 
reservoir and is re-circulated after cleaning. 



127 



PLANT MAINTENANCE MANUAL 



These systems are of two kinds of feed, 
gravity and force. In gravity systems the oil 
supply tank is located above the bearings to 
which the flow of oil is by force of gravity. 
The used oil is returned to the tank by pump- 
ing, after the oil has been filtered or run 
through a centrifuge and a cooler. 

The force feed system operates similarly to 
the gravity feed, except that the oil is pumped 
directly to the bearings, thus doing away with 
the overhead supply tank. 

Care of Oiling Systems 

For best results any oiling system should be 
properly and regularly maintained. 

If hand oiling is used, be sure to oil at 
frequent and regular intervals. The cups and 
reservoirs of bottle, wick or siphon oilers and 
mechanical systems should be filled often 
enough to prevent them from becoming empty. 



A regular schedule for inspecting and keep- 
ing them full should be followed. 

Clean the lubricators from time to time and 
do not let them get filled with dirt and foreign 
matter. Above all, do not let them run empty 
or dry. 

In a splash system it may be good practice 
to draw off a few gallons of oil for treatment 
by running through separation and filtration 
apparatus to remove water, sludge and im- 
purities. The return of the purified oil and 
some fresh oil to the system helps to keep the 
vitality of the oil high and increase the life 
of the oil. 

When oil rings are used for lubrication see 
that they are round and that they turn freely. 
In force-feed systems, make sure that piping 
and oil passages are not plugged. The sys- 
tems should be drained periodically and 
cleaned thoroughly. 




128 




CHAPTER 73 



BALL AND ROLLER BEARINGS 



There are two general types of anti-friction 
bearings— ball and roller. They differ as their 
names imply. Several representative kinds of 
each type are illustrated. 

Generally speaking, an anti-friction bear- 
ing consists of two rings, the rolling elements, 
and a separator. An exception to this gen- 
erality is the needle roller bearing which does 
not have a separator and may or may not 
have an inner ring. 

The instructions presented and the illustra- 
tions of types, methods and equipment shown 
in this chapter were based on practices sug- 
gested by the Anti-Friction Bearing Manu- 
facturers Association, Inc. These procedures, 
which cover the types of bearings most gen- 
erally used, should be of assistance in the 
proper handling of bearings and of help in 
protecting bearings from damage. In addi- 
tion, there are presented accepted methods 
of removing, mounting, cleaning and inspect- 
ing bearings. 

It is always well to refer to the manufac- 
turer's instructions and technical manuals for 
complete details on the company's products 
and for specific data on specialized types of 
bearings. 

New bearings have been correctly as- 
sembled, carefully cleaned, thoroughly treated 
with a protective coating, wrapped in grease- 
proofed paper, and packed in a carton or 



other container or covering by the manufac- 
turer. 

So - 
DON'T Take a new bearing apart. 
DON'T Wash oil or grease out of a new 

bearing and until ready to use them— 
DO Keep bearings in original cartons and 

wrappings. 




Leave bearings in their cartons 
until ready to use them. 



DO Store bearings in a clean, dry place, 

which is not subject to heat extremes. 
Handle bearings as little as possible be- 
cause finger marks are hard to remove and 
perspiration may start corrosion. When nec- 
essary to handle bearings, do so with clean- 
dry hands, plus a clean cloth or rag. 



129 



PLANT MAINTENANCE MANUAL 



GENERAL TYPES OF BEARINGS 



BALL BEARING 



-*| width U- OD 

' ly — Corn* 



Corner 



Shoulders 




Separator 



Outer Ring 
Ball Race 



o 

Y77Y/, 







Single 
Row 



Double 
Row 



Radial- 
Thrust 











on 


.'-7 '\.'/7/A 



Duplex 



Shielded 



Single 
Seal 



Snap 
Ring 



l g a 



3S O O 

Self- Magneto Front 

Aligning Wheel 



Outside Diameter 
- Bore 




BALL THRUST BEARING 



OD. 
Corner 



Bore Corner 



•Face, 



Separator 



m 



59 W 

Flat Seat Self-Aligning Banded or 

Open Open Shielded 

Grooved Race Grooved Race Grooved Race 



STRAIGHT ROLLER BEARING 



—I WIDTH I— 



Outer Rin6 



Inner Ring 



Outside 
Diameter 



Bore 



Face 




OD. Corner 



Roller 



Shoulders 



Separator 






a 



Separable 
Outer Ring 



a 



o 



Separable Non-Separable 
Inner Ring 



130 



BALL AND ROLLER BEARINGS 



TAPERED ROLLER BEARING 




Single Double 

Row Row 



SELF-ALIGNING 
ROLLER BEARING 







m 






htt$ 


^M^. 



Concave Concave Spherical Roller 
Roller Roller Double 

Double Row Row 



Shell 



NEEDLE ROLLER BEARING 



U L.EN6TH *■! 




Rollers 



Outside 
Diameter 



KINDS OF BEARING LOADS AND 
HOW LOADS ARE TRANSMITTED 



RADIAL LOAD - At right anglet to the shaft. 





THRUST LOAD - In a 


in* par 


allel to shaft. 






W^Mm 










Ball. 




Tapered Roller 







Ball. 



Straight Roller. 



ANGULAR LOAD — Combination of radial and thrust. 





Ball. 



Tapered Roller 



131 



PLANT MAINTENANCE MANUAL 




Handle bearings with care and 
with clean hands and rags. 

Dirt is Dangerous 

Dirt is dangerous and will damage bearings. 
Dirt is one of the principal causes of bearing 
failure and wear. 

Therefore — 
NEVER spin a dirty or unclean bearing. 



Never spin a 
dirty bearing 




DON'T handle bearings with dirty hands. 
DO NOT place a bearing on a dirty or soiled 

surface. 
NEVER use dirty or chipped tools. 

Keep Bearings Clean 

If the wrappings or cartons have been 
damaged, check the bearings and clean and 
oil them, if necessary. Then put them away 
in a new dirt-proof carton. If no cartons are 
available, wrap the bearings in water-resis- 
tant paper and seal and label the package in 
some manner for the proper identification of 
the contents. 

When it is necessary to work on bearings 
be sure that the table or bench on which they 



are placed before, during and after working 
are perfectly clean. Use only clean tools and 
clean solvents and flushing oils. Wipe bear- 
ings with clean, lint-free rags only. 

Before trying to judge the condition of 
bearing, clean it. 

Bearings with shields or seals on both sides 
-DO NOT WASH. Wipe outside clean to 
keep dirt from working inside. If bearing turns 
smoothly, coat it with protective lubricant be- 
fore using, or wrap it and store it, if not 
needed right away. 

Bearings with seals or shields on one side 
— Wash and inspect in the same way as those 
without shields or seals, as shown below. 

Bearings with removable seals — Remove 
seal first, then wash and inspect the same as 
those without seals. 

CLEANING BEARINGS 

Soak bearings in solvent long enough to 
loosen grease and dirt — for several hours 
or longer if necessary A clean grease can or 
bucket is a satisfacloy container for washing, 
but a small tank and wire baskets are better. 
Slosh bearings or agitate baskets in the tank. 

Rinse with cfean solvent — light oil or kero- 
sene. 

Dirt, scales, or chips may be removed with 
a clean, short bristle brush. 

An oil spray gun cleaner is very effective 
and often desirable provided a filter is used 
in the air line. Turning one of the races slowly 
by hand — not by the air — will help dislodge 
the dirt. 

An air hose may be used for drying a bear- 
ing provided the air is filtered free from dirt 
and moisture. But DO NOT spin the bearing 
with the air from the hose. 

After drying, the bearing should be lubri- 
cated by dipping in a clean, light spindle oil. 
After cleaning and oiling the bearing, put it 
away in a box or other covered container 
while it is awaiting inspection. 




Dirt is one of the principal 
causes of failure and wear. 



Clean tools and work tables 
help to keep bearings clean. 



132 



BALL AND ROLLER BEARINGS 



CLEANING BEARINGS 



Soak bearings in solvent and 
nse them in clean solvent. 




Basket and tank cleaning are 
better than washing in a pail. 




An oil spray gun is very effec- 
tive, if air line has filter. 




Drying with air is all right if the 
air is clean and dry. 




Put clean bearings in a covered 
box, even for a short time. 




Coat with protective grease if 
storage is for longer time. 




Grease - proofed paper keeps 
lubricant from running away. 




Use water-resistant paper, if no 
cartons are available. 



133 



PLANT MAINTENANCE MANUAL 




REMOVAL 



Blocks strip off bearing while 
ram pushes against shaft. 



^■\jM 



An arbor press serves equally wel 
for removing and mounting. 




Wrong Correct 




Support blocks bear against tight ring or both. 



Bearing pullers either pull or push bearings into place. 




Cleaning Solutions 

Kerosene is often used as a cleaning fluid. 
Anti-knock gasolines containing ethyl or other 
compounds are poisonous in cuts and when 
inhaled. So extreme caution should be dis- 
played when they are used. 

Special petroleum solvents are available 
and are preferred. But since many solvents are 
inflammable, care must be shown in their use 
also. 




BRASS OH OTHER 
SOFT METAL SLUG 

BEARING BORE 



A soft metal slug may be used 
to drive shaft out of bearing. 




Never remove a bearing by 
hammering directly on the bearing. 



Removal 

Care should be taken in removing bearings 
to avoid damaging them. Since the applica- 
tion of force is usually necessary, use the 
right tools correctly. 

The bearing ring that does the turning 
nearly always fits tightly, while the stationary 
ring may be loose. In the case of bearings 
made of separable parts, both rings may often 
be tight fits. 

In removing the bearing then, the press or 
pull should be applied only to the ring which 
is tight, or to both rings evenly. NEVER press 
or pull, if possible, against the loose ring or 
the shields or seals. 



134 



BALL AND ROLLER BEARINGS 



The press or pull should be straight, square, 
and even in order to avoid cocking. 

One of the best tools for removing a bear- 
ing is an arbor press. If a bearing is to be re- 
moved from a shaft, for instance, be sure that 
the support blocks bear against the inner ring, 
or both rings if the bearing has a flush face. 
Make certain that the press table and blocks 
are clean and square. 

The press ram pushes against the shaft, and 
the blocks strip the bearing from the shaft. It 
is also important to prevent the bearing or the 
shaft from dropping on the floor when they 
are separated. 

If an arbor press is not available, a bear- 
ing puller should be used. Be sure that the 
puller is set so that the pull or push will be 
straight and square. 

While the practice is not recommended it 
may be necessary at times to use a vise, drift, 
and hammer instead of a press or puller. If 
so, use a wood block or copper sheet to pro- 
tect the bearing from directly contacting the 
vise, and keep the shaft clear of the vise. A 
slug of brass or other soft metal, with a bore 
smaller than that of the bearing, may be used. 

NEVER pound directly on the bearing or 
rings to remove it. 

Mounting 

Remounting bearings processes are the re- 
verse of those for removal. 

So also in the mounting practices, cleanli- 
ness is the first consideration. See that every- 
thing is CLEAN — the bearings, bearing seats 
and housings, shafts, assembly bench, and 
mounting tools. 

A light coat of oil dropped on the bearing 
seat of the shaft makes mounting easier and 
heips to prevent scoring of the shaft. 

Press the bearing on straight and square 
until it seats against the shoulder in its correct 
location on the shaft. Pressure should be ex- 
erted only on the ring which takes the tight fit. 

In mounting bearings the use of an arbor 
press is recommended, if one is available. 
Avoid excessive force and use care in apply- 
ing the pressure so as not to damage or 
scrape the shafts, or threads if there are any. 

It is most important that the bearing be 
started straight and not out of square align- 
ment. 

Where the distance from the end of the 
shaft to the bearing seat is quite short, the 
shaft may be set in a vise, and the bearing 
pressed on the shaft with a short tube or pipe 
which is clean inside and out and whose ends 
are square. 



Light oil on bearing 

seat of shaft makes 

mounting easier. 



NEVER DO 
-THIS 





A short tube or 

pipe with square 

ends may be used 

with press. 



Never seat a bearing by 
hammering directly on it. 




Place blocks so 

that they clear 

any threads 

on the shaft. 




A wooden block 
may be used to 
cushion hammer 
blows on tube. 



When bearing is 

on shaft straight, 

drive to a firm 

seating. 




If an arbor press is not available the tube 
or pipe may be tapped evenly with a ham- 
mer. In order to avoid cocking, blows should 
be applied alternately at points opposite to 
each other. If desired a block of tough hard 
wood may be used at the striking end of the 
tube to cushion and distribute evenly the ham- 
mer blows. 

NEVER seat a bearing by hammering direct- 
ly on the bearing. 

If the bearings are large it may be neces- 
sary to heat them sufficiently so that they will 
fit over the shaft and be seated correctly. 



135 



PLANT MAINTENANCE MANUAL 



LUBRICATION 

When lubricating bearings be sure to use 
the right kind of lubricant. Use only clean oils 
and greases because dirt is a trouble maker. 

Manufacturers supply lubrication charts for 
their bearings. These charts specify the kind 
of oil and grease to apply — also the amount 
and the frequency. Use only the recommended 
lubricant. If it is absolutely necessary at any 
time to substitute other oils and greases make 
sure that they have been approved for the 
particular application. 

DO NOT use too much oil or grease. Over- 
lubrication may cause over-heating, especially 
in bearings that run at high speeds. Too much 
grease in housings will force the grease out 
past 'the seals and closures. DO NOT pack 
the housings of grease-lubricated bearings 
more than one-third to one-half— never over 
two-thirds— full. 

Handling and Storing Lubricants 

As much attention should be paid to keep- 
ing lubricants clean and free from contamina- 
tion while handling and in storage, as is 
shown to the bearings themselves. 

In order to insure clean lubricants, store 
them in clean containers, and make sure that 
the latter are kept clean. It is essential also 
that the tools used in greasing — grease guns 
and paddles — are perfectly clean. 

Seals and vents should be inspected regu- 
larly for proper lubrication. 

INSPECTION 

Bearings should be inspected for service- 
ability immediately after cleaning. 

If a bearing cannot be separated it may be 
visually inspected by holding the inner race 
in such a way that the bearing is vertical. 



Then rotate the outer race. If the bearing feels 
rough or sticks at certain points, yet no defects 
are visible, the condition may be overcome 
by re-cleaning. If the bearing still sticks or is 
rough, it should be examined closely for the 
cause of the trouble before it is rejected. 



Defects Calling for Rejection 

Bearings should be rejected if they show the 
following defects: 

WHAT TO LOOK FOR 
Breaks, cracks, rust, flaked 
areas. 

Indents, flaked areas, rust. 
Breaks, cracks, fractures. 
Dents, bends, breaks. 
Breaks, cracks, bends. 



PART 
Balls and rollers 

Raceways 

Rings 

Seals or shields 

Separators 

General: 

Discoloring 



Moderate is not harmful. 
Dark discoloring from over- 
heating. 

Bad from inadequate sup- 
ply of lubricant. 
Looseness or If excessive, compare it 

end play with a new bearing. 
Roughness If it continues after cleaning 

or flushing. 
Bearings which pass inspection but cannot 
be re-used for a few days should be treated 
with a preventive lubricant and placed in a 
clean container. 

If such storage is for a longer time, the 
bearing should be dipped in a rust preventive 
and coated with a light protective grease. 
Then it should be wrapped in a grease-'proof 
paper and put in a box or carton. If cartons 
are not available, wrap in water-resistant 
paper. 




Cracked inner ring — may result from 
wrong fit or improper force. 





Broken separator — this is often caused 
by dirt or metal chips. 



To inspect bearing, hold inner ring 
as shown and rotate outer ring. 



136 



BALL AND ROLLER BEARINGS 





Dented shield — this damage was caused 
by a drift that slipped. 



Roller markers on inner race — impressed 
balls or rollers may do this. 





m 

1101111011 



Spaded cone, cup, and rollers of bearing 
— showing some flaked areas 



Dented shell or outer race — from the 
wrong use of hammer and chisel. 




Etched cone of tapered bearing — 
formation from moisture or acid. 



137 




CHAPTER 14 

- WIRE ROPE 



In most types, wire rope is a helicaharrange- 
ment of strands of wires around a core or 
center. Wires are laid helically into strands 
and strands into ropes with a definite pitch in 
which each wire functions as a related mem- 
ber of the whole. There are other types of 
wire rope, but the helically designed is the 
most widely used by industry. Most ropes have 
six strands, although more strands are used 
where greater roundness or flexibility is de- 
sired. 




~w: 




Preformed Wire Rope 

In ordinary wire rope the strands of the 
rope are under internal stress, so that when 
the ends are not held together by serving or 
by some other means, the strands will tend to 
spread apart. In PREFORMED rope the wires 
and strands pass through a special process 
before they are assembled into rope. In this 
special process the wires and strands are 
given the helical shape that they will later 
assume when they are assembled into rope. 
Loose ends of preformed wire rope do not 
tend to become untwisted. In addition pre- 
formed wire rope offers other advantages, 
such as the minimizing of internal stresses 
which often causes individual wires to break 
before they have reached the end of their 
useful lives. 

Structure Sections 

Six strand ropes are made in a variety of 
constructions. One of the most widely used is 
the 6 x 19, in which description the larger 




6 x19 Filler Wire 



138 



WIRE ROPE 



figure refers to the number of main wires in 
each strand. Other typical rope constructions 
are shown on the next page. 

Rope centers generally fall into two classes 
— fiber cores and metallic cores. A fiber core 
forms a resilient foundation for the strands 
and supports the rope structure. Due to the 
core's original impregnation with lubricant and 
its capacity to absorb lubricants, it serves 
as a source of lubrication for the rope. Fiber 
cores consist of manila and sisal, and, for 
small ropes, cotton, jute and mauritius. 

Metallic Cores 

Metallic cores consist of independent wire 
rope cores (IWRC) or wire strand cores. 
These are generally used where the rope is 
subjected to severe crushing on drums,- for in- 
creased strength and for resistance to ex- 
cessive heat. 

Rope Grades 

The wire in wire ropes is usually designated 
as made of improved plow s*eel, plow steel, 
mild plow steel, traction steel, iron, stainless 
steel and bronze. Ropes made of these mate- 
rials each have various characteristics that 
permit one or more of them to fit almost every 
industrial requirement. 

Rope Lays 

Rope may be either right or left lay. A 
right lay rope is one in which the strands pass 
from left to right across the top of the rope, 
similar to a right hand screw thread. In a 




left lay rope, the strands pass from right to 
left, similar to a left hand screw thread. 

A regular lay rope is one in which the lay 
of the strands is opposite in direction to the 
lay of the wires in the strands. In a Lang lay 
rope the lay of the strands and the wires are 
in the same direction. A right or left lay rope 
may be either regular or Lang lay. A regular 
lay rope is more stable and offers better 
resistance to distortion on a drum, than does 
a Lang lay. Lang lay ropes offer greater re- 
sistance to abrasion and bending fatigue than 
regular lay ropes. 

SELECTION 

Wire rope has been termed a machine that 
must be designed to fit the various operating 
conditions under which it is to be used. 

Load 

A safe and economical practice in select- 
ing rope to meet certain load conditions, is 
to pick a rope whose breaking strength is 
about 5 times the working load. Higher fac- 
tors of safety should be used where human 
life may be endangered if the rope breaks. 

Drums and Sheaves 

The sizes of drums and sheaves are also 
determining factors in the selection of rope. 
More flexible constructions must be selected 
when drums and sheaves are small. 

Abrasion 

In general, ropes constructed of coarser 
strands have more resistance to abrasion than 
the finer strand, more flexible ropes. Where 
both abrasion and bending are important con- 
siderations, it may at times be preferable to 
select a rope of coarser strand construction, 
at the expense of flexibility. 

Corrosion 

Ropes provided with a special protection 
for the steel wires are available for use where 
corrosion is a major factor in rope deteriora- 
tion. Stainless steel and galvanized ropes are 
typical of this type. 

Heat 

Where a rope is subjected to intense heat, 
an all steel construction must be selected, even 
at the expense of the greater flexibility of 
fered by a fiber center rope. 

In selecting wire rope for particular types 
of work, it is recommended that manufactur- 
ers' representatives be consulted, as they have 
had experience in solving all kinds of prob- 
lems involving the use of wire rope. 



139 



PLANT MAINTENANCE MANUAL 



Typical Rope Sections 

6x19 Filler Wire is an average rope suit- 
able where resistance to abrasion and bend- 
ing fatigue are of equal importance, as indi- 
cated by the accompanying graph. It can be 
used on rather small sheaves and is widely 
used in the following applications; shovel hoist 
ropes, boom falls, car dumpers, coal hoisting 
towers, elevators, shaft hoists, inclines, skip 
hoists, tackle blocks, slings and draglines. 




6x19 F. W. 

6 x 19 Seale offers greater resistance to 
abrasion than the Filler Wire, as the outer 
wires are larger in size. It withstands crushing 
on the drum but is not as flexible nor has the 
reserve strength of the Filler Wire and War- 
rington construction. It is mainly used on 
draglines, car spotters, crab winches, track 
line on cableways, scrapers and inclines. 




6x19 Seale 

6x19 Warrington is made up of wires of 
four sizes. It is chiefly used for cable tool 
drilling lines and to some extent for tackle 
blocks, boom falls and slings. 




6x19 Warrington 

6x16 Filler Wire construction is adaptable 
to applications where greater resistance to 
abrasion than the 6 x 19 Filler Wire is re- 
quired, and greater flexibility is desired than 
provided by 6 x 19 Seale. It is largely used 
for cargo falls, car haulages, draglines, in- 
clines and slope haulages. 




6x7 construction provides strong resistance 
to abrasion. It is. not very flexible and its uses 
are confined to applications where it encount- 
ers few sheaves and drum of small diameter. 
It is used for car haulage, inclines, transmis- 
sion, guys and standing rigging. 




ABRASION VS BENDING FATIGUE 


This chart shows why 6x19 Filler Wire construction 


might be termed an average rope. Has a medium 


resistance to abrasion and bending fatigue. 


MIN MAX. 


4x7 

4x13 F.W. 
4x1? SEALE 


VAMANCf o» oum w«f sins 




/ 


4x14 F.W. 


3l • ■• 




4x19 WARR. 






4x19 F.W. 




•x19 SEALE 
4x22 *.W. 
4x37 SEALE 
4x41 
4x19 WARR. 


/ 




•xl* F.W. 











6x16 F.W. 



Wire Materials 

The wire in wire rope is generally made of 
one of the following materials. 
IMPROVED PLOW STEEL:. Possesses highest 
strength and toughness and most wear resis- 
tant properties. Good for heavy duty services. 
About 15% stronger than Plow Steel. 
PLOW STEEL: Very good strength and tough- 
ness and fatigue resisting properties. About 
15% stronger than Mild Plow Steel. 
MILD PLOW STEEL: Combines toughness and 
pliability and capable of undergoing repeated 
impact stresses. 

TRACTION STEEL: High resistance to bending 
fatigue and imparts a minimum abrasive force 
on tread surfaces of sheaves and drums. 
Widely used as hoisting ropes applied to 
Iraction type elevators. 

IRON: Low tensile strength but very ductile. 
Widely used in elevator service. 
STAINLESS STEEL: High corrosion resistance. 
Widely used in the marine field, in aircraft and 
industrial applications where corrosion or tem- 
perature conditions are excessive. 



140 



WIRE ROPE 



HANDLING 



Unreeling and Uncoiling 

Once a kink has been made in a wire rope, 
no amount of strain will remove it and the 
rope is unsafe for use. It is imperative, there- 
fore, that a rope should be unreeled or un- 
coiled properly so that no kinks will occur. 
When unreeling a rope the reel should' either 
be laid horizontally on a turn table, or raised 



on two jacks on a pipe passing through its 
center. In these positions the rope can be 
pulled directly from the reel without twisting. 
A turn table is also useful for uncoiling a 
rope. The coil is placed on the turn table and 
the rope pulled off as the table turns. If a turn 
table is not-available, the rope can be played 
out by rolling the coil along the ground. 




UNREELING AND UNCOILING 



Applying Seizing 

Seizing, or serving wire can best be applied 
to wire rope by means of a seizing iron. A 
spool of seizing wire is inserted in the yoke of 
the iron and the seizing can be quickly and 
easily applied to the rope. 




APPLYING SEIZING BY MEANS OF HAND CUTTERS 




1. Wind seizing wire around rope 
by hand, applying considerable 
tension on the wire and keeping 
the coils close together. 




2. Twist wire ends together counter- 
clockwise, keeping twisted portion 
near middle of seizing. 



141 



PLANT MAINTENANCE MANUAL 




3. Tighten the twist with "Carew" 
cutters, to take up the slack. Do 
not tighten seizing by twisting. 




4. Pry the twist away from the axis 
of the rope with the cutters, in 
order to tighten the seizing. 



"£ 





5. Again tighten twist as in (3). 



6. Repeat (4) and (5) until seizing 
is tight. Cut off ends of the wire 
and pound twist flat against the 
wire. Finished seizing should ap- 
pear as shown. 



Attaching Sockets 

Seizing should be applied to the wire rope 
at a distance equal to the length of the basket 
of the socket. 




Fiber center of rope should be cut out 
above seizing. 




Untwist strands and broom out the wires. 
Clean wires with benzine, naphtha or other 
suitable petroleum solvent, then dip in solu- 
tion of muriatic acid (50% commercial muriatic 
acid and 50% water) for about 30 seconds. 
Rinse wires in boiling water to which a small 
amount of soda has been added. 




Draw ends of wires together with seizing 
wire, so that socket can be forced down over 
them. Force socket down over wires until it 
reaches seizing. Remove seizing wire inside 
socket, so that wires will expand within the 
basket. 



142 



WIRE ROPE 



* 




Seal base of socket with putty, or clay and 
preheat socket to drive out moisture. Fill 
socket basket with molten zinc at 800 to 875 
degrees F. 

ID. 




Cool and remove seizing. 




Attaching Clips 

The efficiency of clipped attachment is de- 
pendent upon the manner in which the clips 
are applied. The U-bolt portion of the clip 
should always bear against the short end of 
the rope, and the base of the clip should bear 
on the live side of the rope. The center dis- 
tance between clips should be 6 times the 
rope diameter. Tighten nuts equally, with rope 
under tension. Retighten after first few hours 
of continuous service. 




TYPICAL STYLES OF SAFETY SLINGS 




Single loop sling 
with protector arc 



Two-leg sling with 
earn -type hooks 





Safety type of splice 




Use of a safety clamp 
instead of a splice 



143 



PLANT MAINTENANCE MANUAL 



MAINTENANCE 



Like any other machine, wire rope must be 
properly maintained in order to render long 
and reliable service. If the wear on a wire 
rope is not uniform it is sometimes advisable 



to reverse ends to help equalize the wear. 
In other cases sections of rope must be cut 
from the ends ot ropes, or ropes must be 
spliced so as to remove worn sections. 



Lubrication 

Although lubricants are applied as a struc- 
tural part of nearly all wire ropes during 
manufacture, ropes must be lubricated per- 
iodically and in the proper manner, or the 
rope will fail long before its normal life time. 

The frequency of application of lubricants 
to ropes depends on the rope construction, 
load, line speed, amount of abrasion, fre- 
quency and extent of bends, presence of cor- 
rosive materials and other operating factors. 
Under no conditions should the rope parts be 
permitted to lose their protective supply of 
lubricant. 

The rope manufacturer should be consulted 
for the kind of lubricant to use. Cold lubricant 
can be applied by pouring it on the rope as 
the rope passes over a sheave. A swab should 



be held on the rope after it leaves the sheave 
in order to spread the lubricant evenly and 
remove excess. Never hold the swab ahead 
of the sheaves, as the holders hand may be 
drawn into the sheave and injured. 

It is necessary to use a heated bath when 
applying hot lubricant. A method of doing 
this is shown in the accompanying drawing, 
where the rope is passed over end rollers and 
is directed into the hot lubricant by a guide 
wheel. A swab on the incoming side of the 
bath removes dirt from the rope. 

Sometimes it may even be necessary to use 
kerosene and a wire brush to thoroughly clean 
the rope before lubrication. The rope should 
pass through the bath slowly, giving sufficient 
time for the lubricant to penetrate between the 
wires and reach to core. 





MANUAL APPLICATION OF LUBRICANT 








&<^° 


ss 


p%^ fi* ^^ 


V ^w^sBSfe**^: / 




,000400 




APPLICATION <3F HEATED LUBRICANT 



144 



WIRE ROPE 



Cutting Wire Rope 

When cutting wire rope the rope should be 
seized not only close to each side of where 
the cut is to be made, but also in one or 
more spots beyond the first seizing. This as- 
sures that the rope strands beyond the cut 
will not be distorted due to the cutting strain. 




CUTTING WIRE ROPE 



Drums and Sheaves 

Make sure that all sheaves and drums are 
kept in good condition. Replace or recondi- 
tion badly worn or broken members, as they 
will quickly injure the rope which is used with 
them. 

Use sheaves and drums of as large a di- 
ameter as practical, to minimize the bending 
stresses in the rope. Avoid unnecessary bends 
when laying out wire rope installations. 



CAUSE OF ROPE INJURY 

Bad Spooling 

Careless spooling and excessive loads on 
a small, smooth drum cause damage to wire 
rope. 




Overload 

An overloaded rope loses its lay, as shown 
in the accompanying illustrations. 




Pinching and Crushing 

The upper rope shows broken wires on two 
sides of rope caused by a sheave groove be- 
ing worn down to a diameter smaller than the 
rope. Lower rope has been damaged by 
drum crushing. 




Kinking 

A kinked rope leaves the strands distorted, 
as in upper rope. The wires in these distorted 




DRUMS AND SHEAVES 



145 



PLANT MAINTENANCE MANUAL 



strands will soon break, as in lower rope, 
leading to ultimate rope failure. 




Bending 

Small sheaves and drums, or excessive fric- 
tion against sharp objects causes a breakage 
in the wires of the strands. 



that the wires have merely been flattened 
down to a triangular shape, and have lost 
only a small amount of their strength. 

Abrasive wear should not be confused with 
peening, as abrasion is a wearing action that 
quickly reduces the cross section of the rope 
and thereby lessens its strength. 





Peening and Abrasion 

A peened rope often appears as though it 
is badly worn. Close examination will show 



Strand Nicking 

Nicks in the rope strands is another indica- 
tion of overload. 



TO CALCULATE ROPE REMAINING ON A REEL: 



When it is not convenient to weigh a reel in order to 
determine the amount of rope remaining, the fol- 
lowing formula can be used: 

H— height of coiled rope on reel, in inches 

S— diameter of reel barrel, in inches 

L—lnside width of reel, in inches 

D— diameter of rope, in inches 
Length of remaining rope 

(H + S) H x L x 0.262 
in feer= — 




TO CALCULATE MINIMUM SHEAVE AND DRUM DIAMETERS 


D equals the diameter of the rope 


Ro 


pe Construction 




6x7 


6x19 
Seale 


6x16 
F.W. 


6x19 
Warr. 


8x19 
Seale 


6x19 

F.W. 


6x22 
F.W. 


8x19 
Warr. 


8x19 
F.W. 


6x37 
Seale 


6x41 


Minimum 
Sheave 
or Drum 

Diameter 


42xD 


34xD 


30xD 


30xD 


26xD 


26xD 


23xD 


21xD 


21xD 


18xD 


18xD 



146 



WIRE ROPE 



STRESS IN SLINGS 



STRESS IN SLINGS VARIES WITH THE ANGLE OP THE LESS 



i 



500 lbs.- 



IQOO lbs. 




147 




CHAPTER 75 



CHAIN AND ELECTRIC HOISTS 



Hoists are practical and economical de- 
vices for the handling of materials of many 
kinds. The use of modern chain and electric 
hoists saves time and money, improves work- 
ing conditions, lowers manufacturing costs, 
increases worker efficiency and otherwise aids 
production, maintenance and other industrial 
operations. 

Basic designs include hoists for general util- 
ity, close clearances, stationary mounting, 
trolley travel and other specific purposes. 
Some of the highlights of modern chain and 
electric hoists, which are available in a wide 
range of capacities, lifts and speeds, are 
as follows: 

Easily accessible parts 
Brakes of advance design 
Safe, smooth, quiet operation 
High overall mechanical efficiency 
Low operating and maintenance costs 
Highest quality anti-friction bearings 
Simple, compact and practical designs 
Positive safety stops and cable anchorages 
Motors specifically designed for hoisting 

service 
Standardization and interchangeability of 

parts 
Balanced gearing and lasting drive mech- 
anisms 
Super-tough chains, proof-tested before in- 
stallation 



Machine grooved drums and guarded drum 
flanges 

Cables of highest grade flexible steel hoist- 
ing rope 

Operating parts sealed against dust, dirt 
and moisture. 

CHAIN HOISTS 

Chain hoists commonly consist of sheaves, 
gears, hand and load chains, and support 
and load hooks. The mechanisms are such 
that a pull on the hand chain activates the 
sheave and load chain through a differential 
or geared arrangement. 

In the simple differential type of hoist an 
endless chain is looped continuously through 
upper and lower sheaves. The loop which sup- 
ports the lower sheave or load block is con- 
sidered as the load chain. The free loop is 
used as the hand chain. 

The enclosed gears in the geared form of 
hoists may be of either the spur or worm types. 
The worm type is often called a screw hoist. 
In these forms of hoists the pull on the hand 
chain is transmitted to the load chain through 
the reduction gearing. 

Maintenance 

The checking periods given below are 
merely suggestions, assuming a normal daily 
operation of the hoist. The length of these 



148 



CHAIN AND ELECTRIC HOISTS 



Planetary 
spur gears 



Suspension 
hook 



Driving 
pinion 



Suspension 
plate 




Guide for 

hand 

chain 



Swivel bearings 



Load hook 



149 



PLANT MAINTENANCE MANUAL 



periods depends largely on where and how 
often the hoist is used, and also on the par- 
ticular design of the hoist. 

Lubricate all parts intended to be lubricated 
at least monthly; and more often if in ex- 
tremely dusty, hot or wet places. Pay especial 
attention to chain and hooks. 

Guard against lubricating the wrong parts. 
Some types of lever hoists are not intended 
to be lubricated at all. Some differential types 
will not sustain load if given too much oil. It 
is generally necessary to remove the gear 
case when lubricating the planetary gear 
system. 

When lubricating, check load brakes to full 
capacity. Repair or replace if any uneven 
action or any drift is indicated. 

After lubricating, operate all parts rapidly 
under full load and under no load, listen 
carefully for noises which may indicate worn 
gears, sheaves, sprockets, bearings, or loose- 
ness of any parts. 

When lubricating, clean the outside of the 
case thoroughly and look for signs of oil leak- 
age indicating faulty bearings or shields, or 



spillage indicating that too much lubricant has 
been used. 

Lubricate load chains monthly even though 
no other parts of the devices on which they 
operate are to be lubricated. Make sure lu- 
bricant gets into the contact points of the links. 

Inspect loaded hook monthly. If any sign of 
spreading, suspect damage to hoist parts due 
to overloading or other abuse. Never wrap 
load chain around load. 

Measure load chain at least annually. If 
length of any 20 consecutive links exceeds 
proper length by as much as 3% analyze the 
chain for replacement. 

Inspect chain monthly for signs of such 
abuse as hooking load hook over chain in- 
stead of using slings,- if one or two links are 
damaged have new section of chain inserted 
by hoist manufacturer. When frequent short 
lifts are made in the same section of the load 
chain and wear occurs, the load chain can 
be reversed end for end, in order to put a 
new section in service over the load sheave. 

Inspect, lubricate and maintain all overhead 
parts such as trolleys and wheels monthly. 



DIFFERENTIAL HOIST 

To lift load 1 ft., 
30 ft. of chain 
must be handled. 



SPUR GEAR HOIST 

To lift load 1 ft., 
31 ft. of chain must 
be handled. 




« 



4 190 lbs. 



1 ft. 



Mechanical efficiency 
approximately 35%. 



i! 



I ^76 lbs. 



1 Ton 



_1_ 1 ft. 



Mechanical efficiency 
approximately 85%. 



SCREW GEAR HOIST 

To lift load 1 ft., 

57 ft. of chain must be 

handled. 



87 lbs. 




Mechanical efficiency 
approximately 40%. 



150 



CHAIN AND ELECTRIC HOISTS 



TYPICAl 
APPLICATIONS 



OF CHAIN HOISTS 




Mounted on extension 
beam from a stake truck. 



Jl 1 


1 oSC* 



Mounted on an overhead 
crane traveler. 




Mounted on a straight 
overhead trolley. 




Used for dismantling 
heavy machines. 




Mounted on an overhead 
beam of a delivery truck. 




Mounted on an I-beam in 
a warehouse. 







Overhead mounting for 
use on a production line. 




Twin hoists mounted on 
overhead crane traveler. 



151 



PLANT MAINTENANCE MANUAL 




Mounted on a cross-frame 
over a processing pit. 




Mounted on a curved over- 
head trolley system. 




Mounted on overhead- trol- 
ley above processing vats. 



TYPICAl 

APPLICATIONS 

OF CHAIN HOISTS 




Mounted on a portable 
lifting frame. 




Use on a circular trolley 
system over processing 
vats. 




Mounted on multiple trol- 
ley system to cover com- 
plete floor area. 




152 



CHAIN AND ELECTRIC HOISTS 



ELECTRIC HOISTS 

Electric hoists are supplied in a wide range 
of types, sizes, capacities, operating speeds 
and lifting heights. 

Where mounted applications are for sta- 
tionary overhead use, the mountings may be 
of bolted constructions or hook suspension 
devices. Base mounted hoists find advantage- 
ous employment for drawing loads laterally, 
for opening and closing doors and other like 
applications. For overhead crane, tramrail or 
monorail track travel, the trolleys may be 
made of the- push, hand-chain gear operated 
or motor driven types. 



Motors specially built for the service are 
used in electric hoists. The motors are usually 
controlled from the ground by means of pend- 
ant ropes or pull cords, or by push button 
devices. Variable speed arrangements are 
also available. Many of the floor operated 
types of electric hoists can be converted for 
monorail cab operation. 

Recent developments in electric hoists in- 
clude those which are designed to serve a 
variety of industrial purposes. These modern 
hoists can be easily hung up and readily 
plugged inro the nearest electric socket and 
put to work immediately. 




<fr 



ii 

1! 







LA 



STv^ 



6 



i 





J=fB= 



S*T. 




153 



PLANT MAINTENANCE MANUAL 




154 



CHAIN AND ELECTRIC HOISTS 



Operation 



Many different kinds of employes in a plant 
often use the electric hoists. If these people 
can be taught a few fundamentals of correct 
hoist operation, hoist maintenance can be 



greatly reduced and the useful life of the 
hoist increased. Below are listed a few points 
on hoist operation that should be brought to 
the attention of hoist operating personnel. 




1. Keep the pull of the load 
tangent to the drum or 
sheave. 




2. Suspend load from throat 
of hook, not the point. 





J. Do not use electrical con- 
trol cable to pull hoist. 



4. Do not overload hoist. 




5. When hoist is not in use, be sure 
hook and pendant controls are 
pushed out of the way. 




6. Where hoists do not use electric 
power for traveling, use track clamps 
for holding on even the slightest 
grades. Use ratchet or geared movers 
for close spotting. 



155 



PLANT MAINTENANCE MANUAL 




7. Do not tamper with limit switches. 




8. Use motor propulsion with re- 
mote control, rather than pendant 
push button control alone, if travel- 
ing speed is a factor in production 
speed. 




9. Report any looseness or irregu- 
larities in the track, worn cable or 
chain, or abnormal operation of 
the hoist. Do not attempt repairs 
yourself. 




10. Do not leave hoists standing 
loaded over long periods. 



MAINTENANCE 

The checking periods given below are 
merely suggestions, assuming a normal daily 
operation of the hoist. Each checking period 
is really an individual case, depending, among 
other things, on the type of hoist, its frequency 
of use, the atmosphere it must work in, etc. 

]^ Once Each Day . . . 

Operate hoist over full travel, to see that it 
functions smoothly and the brake operates 
properly. 

Trip limit switches to check their correct 
operation. 

\S Once Ecch Month . . . 

Check the load cable or chain for signs of 
abuse. The cable or chain is apt to be the 
first part to show signs of abuse, if a chain has 
stretched as much as 3%, replace it. 

Inspect the load hook and its fastening to 



the cable or chain. Look especially for signs 
of loads having been applied to its point in- 
stead of its middle. 




Check motor brake for correct adjustment. 
Check the load brake for any irregularity of 



156 



CHAIN AND ELECTRIC HOISTS 



operation or any drifting at full load. Adjust 
or repair at once, if needed. 

Lubricate carefully, following the manufac- 
turer's instructions and using the proper lubri- 
cants. An electric hoist has electrical and 
mechanical elements assembled in a small 
space. Extra care must be taken to prevent 
lubricants getting into the electrical parts. 




Keep cable or chain lubricated to reduce 
wear and corrosion. 

Put hoist on regular electrical maintenance 
schedule, so that motor and electrical parts 
will be serviced properly. 

Inspect breathing holes on oil cases to make 
sure they are not plugged. If they become 



plugged, heat may force oil into electrical 
parts. 

Check casing and all air circulating pas- 
sages for cleanliness. Blow out or clean, if 
necessary, as the hoist must dissipate heat 
from large areas of casing surfaces. 

Inspect wheels for signs of wear,- track for 
levelness and for true joints,- and all position- 
ing apparatus for accuracy. 




Operate hoist under no-load, trying every 
speed and every function, including traveling, 
reversing by limit switch, taking curves, hoist- 
ing and lowering. Listen for noise indicating 
loose or worn parts. Check and tighten any 
loose bolts, screws, parts, etc. 



ELECTRIC HOISTS SERVE 
IN A WIDE VARIETY OF USES 




Hoist mounted on manually 
operated overhead trolley. 




Raising materials from one 
floor to another. 



157 



PLANT MAINTENANCE MANUAL 




Used over assembly line. 




Mounted on jib crane to han 
die steel shapes. 





Mounted on jib crane to han- 
dle rolls. 



Hoist with extension for han 
dling large parts. 





Twin hooks mounted on crane 
bridge. 



Usea with spreader for han- 
dling large molds. 



158 



CHAIN AND ELECTRIC HOISTS 




Mounted over long work 
bench. 




Used to facilitate machine 
loading. 




Used for handling bundles of 
steel sheets. 




Used with power trolley in 
large warehouse. 



159 




CHAPTER 16 



INDUSTRIAL CONVEYORS 



Conveyors of many kinds serve a multitude 
of materials-handling tasks in the modern in- 
dustrial plant. In fact, the efficient production 
of goods today would not be possible without 
one or more forms of these handling aids. 

Practically any sort of materials— bulk or 
packaged— can be carried by conveyors of 
one kind or another in capacities required for 
their economical movement, since capacities 
depend, to a large extent, on conveyor size 
and speed. 

Goods are moved along conveyors by 
manual power, by the pull of gravity on them, 
or by power generated by some mechanical 
means such as an electric motor, gas engine 
or other prime mover. Air power, too, may be 
used as the propelling force. 

The nature of the movement may be hori- 
zontal, inciined or vertical. And even in a 
single conveyor installation, the system may 
elevate and lower goods as well as carry 
them along a level line. 

Transporting media include belts, rollers, 
wheels, slats, wire mesh, scrapers, flights, 
chains, screws, buckets, aprons, and overhead 
track arrangements of various sorts. 

Fundamentals 

Most conveyor installations are made up of 
standard units or sections of one kind or 
another. Nevertheless, almost every conveying 



job is "tailor made" to meet the specific prob- 
lems faced in each mill and factory and in the 
differing requirements encountered in the dif- 
ferent departments in the plant. 

It is important, therefore, that the manufac- 
turers of conveyor equipment be consulted in 
order to obtain the most suitable method or 
methods and the best possible coordination of 
all units and accessories needed for the spe- 
cific materials-handling operations involved. 

Among the factors that influence the selec- 
tion of the right equipment are such consider- 
ations as the following: nature, weight, volume 
of material handled; kind of flow, continuous 
or intermittent; distances of the various move- 
ments; manufacturing methods and processes,- 
sequence of operations; plant equipment lay- 
out and floor arrangement; the power require- 
ments and the sources of power available,- 
and the permanence of the installations. 

ROLLER AND WHEEL CONVEYORS 

Wheel conveyors roll goods on small wheels 
which extend above the frame. The wheels 
revolve in fixed bearings, usually of the anti- 
friction type; and they are properly spaced 
for sufficient support on axles that run across 
the frame or on longitudinal runners along 
the framework. 

Roller conveyors are made up of a succes- 
sion of rollers so spaced as to provide a con- 



160 



NDUSTRIAL CONVEYORS 






GOOD 



CONVEYOR 



THE BIG M0f MA|NTE NANCE 



ARE- 



?. INSPECT 

2. LUBRICATE 

3. SERVICE 

4. CLEAN 



REGULARLY 




TWO "NEVERS" IN LOADING CONVEYORS — 
NEVER OVERLOAD AND NEVER LOAD CARELESSLY 



161 



PLANT MAINTENANCE MANUAL 



tinuous, rigid riding surface. The rollers, which 
turn in fixed bearings commonly of the anti- 
friction ball or other free-running kind, may 
be cylindrical or conical or of some other 
curved shape. 

The conveyors may be made up of single 
rollers extending axially across the frame, or 
two or more rollers may be mounted on the 
same shaft. The two- or three-roller construc- 
tions are particularly suited for curved sections. 

Conveyor rollers are usually set horizontally 
in their frames. They may, however, be ar- 
ranged at an angle to form a "V" shaped 
trough for handling tubular goods. 

Switches, frogs, Y sections and turntables 
are available for changing the direction of 
travel or routing of the goods carried. 

Roller conveyors run either on a level, re- 
quiring manual power for moving the goods 
along them, or they may have a slight grade 
in order to take advantage of the pull of 
gravity. 

fhese conveyors may also be power driven. 
Rotation is transmitted to the rollers in several 
ways. One method is by means of flat or 
round belts which press against the under side 
of the carrier rollers. The pressure is aided by 
appropriately placed snubbing rollers. In live 
roller conveyors employing this belt drive, the 
snubbing or activating rollers should be just 
high enough to supply sufficient contact be- 
tween the belt and the carrier rollers to per- 
mit them to move the goods. 

The care of these belts is similar to that for 
regular conveyor belts, a subject which is 
covered later in this chapter. 



Rollers may also be made "live" by chain 
and sprocket arrangements. Good mainten- 
ance suggestions for the care of conveyor 
chains are obtained in the chapter on trans- 
mission chains. 

Preventive Maintenance 

Testing the operation of a roller conveyor 
once a month is usually a sound maintenance 
practice for the prevention of trouble. This 
test may be accomplished by running some 
representative item along the entire line in 
order that the operation of the rollers may be 
observed throughout the travel. 

Each rolling part should turn easily; and in a 
gravity system it should revolve several times 









U^F 




Elitei 










162 



INDUSTRIAL CONVEYORS 



after the test piece has passed over it. Rollers 
which do not perform properly should be ex- 
amined for binding, for mis-alignment and for 
badly worn bearings. 

Dirt and rust cause pinching and binding. If 
bearings pinch or bind, some manufacturers 
recommend that the bearings be cleaned and 
relubricated with oil or grease. On the other 
hand, other makers advise that their rollers 
and bearings be run dry. So be sure to follow 
the manufacturer's recommendations in this 
respect. 

Where anti-friction bearings are grease- 
sealed, they should be re-greased at regular 
intervals with a hand pressure grease gun. If 
steam or water or any other moisture causes 
are present, the re-greasing is particularly im- 
portant. 

Bearings of the oil impregnated sort which 
automatically oil themselves during use even- 
tually require re-oiling from time to time. 
These bearings should also be inspected for 
wear. 

Periodic lubrication will help to prevent in- 
terruptions to service. 

The framework, stands, and roller supports 
should also be inspected periodically to see 
that they are firm and that the fasteners are 
not loose. 

CHUTES 

Chutes, one form of gravity conveyors, may 
be straight or spiral. The latter kind is used 
where the available space is too limited for 
a straight chute or where delivery immedi- 
ately below a given point is desired or where 
control of the speed of the commodity is 
important. 

In maintaining chutes, see that the runways 
are clean at all times. This check is especially 
important where dirt may be present or has 



accumulated on the bottom of the packages 
or items handled. 

Both straight and spiral chutes may have 
rollered runways, the latter being commonly 
referred to as roller-spiral conveyors. The 
rollers should, of course, be inspected periodi- 
cally for free-rolling. Maintenance proced- 
ures for these rollers are the same as those 
for the usual roller conveyors, which recom- 
mendations are given elsewhere. 

BELT CONVEYORS 

In belt-conveyor systems, materials are 
carried on moving endless belts which are 
supported on rollers, pulleys or runways 
mounted on appropriate supports and frame- 
work. The belt is usually driven by a pulley 
or pulleys which turn in fixed bearings and 
are mounted on shafts. The drive pulley gets 
its power from a prime mover transmitted 
through belts, chains, gears, speed reduction 
units or other means of power transmission. 

Other components of a belt conveyor sys- 
tem include the take-up devices for maintain- 
ing belt tension; chutes or hoppers for loading 
the belt; and chutes, scrapers, plows or trip- 
ping devices for unloading. Housings, gal- 
leries, decks, or other coverings also are 
provided when desirable or necessary. A belt 
cleaning device should be used where sticky 
materials are handled. 

Kind of Belts 

Rubber belts are widely used in conveyor 
work. The rubber belts are built up of several 
plies of cotton fabric bonded together with 
a rubber compound, over which is laid the 
rubber cover. A tendency today is to use 
high grade covers and carcasses possessing 
high friction with skim coats between the plies. 
The carcass, which is the strength carrying 




163 



PLANT MAINTENANCE MANUAL 



member, may also be made up of plies of 
cords imbedded in rubber. Top covers are 
supplied with varying degrees of abrasion re- 
sistance to meet the many different kinds of 
materials handled. 

Canvas belts are another kind. They consist 
of layers of cotton duck, in ply or folded 
construction, sewed together and water- 
proofed. Belts of balata and wire mesh are 
also found in conveyor installations. 

Belts are operated either flat or troughed. 
The former are usually used for handling 
packaged goods while the latter are more 
suitable for the handling of bulk materials 
because they reduce spillage and provide 
greater capacity. On the return part of the 
travel, however, troughed belts are usually 
run flat. Troughing of belts is accomplished 
by inclining the outer rollers. 

Manufacturers of conveyor belting and belt- 
conveyor systems should be consulted for 
their recommendations in regard to the best 
kind of belt and its application to meet various 
service conditions and the requirements of 
the materials handled. 

Joining Belt Ends 

Belt ends can be joined together by means 
of metal fasteners, such as metal plates with 
rivets, projecting prongs, or bolts of various 
kinds. 

Vulcanizing is an excellent way of joining 
the ends of a rubber conveyor belt. Be- 
cause of the difficulty of installing an endless 
belt over the pulleys and rollers of a conveyor 
system, belt ends are seldom spliced and vul- 
canized at the factory before shipping. Port- 



able vulcanizing presses, however, are avail- 
able in most parts of the country for join- 
ing the belt ends "in place" on the job. These 
devices are obtainable from the makers of 
the presses or of the belts. 

These manufacturers issue completely de- 
tailed instructions on the way to make per- 
manent splices. The instructions, which can be 
successfully employed by any intelligent me- 
chanic, should be followed carefully. 

In brief, the two ends of the belt are cut 
back ply by ply and matched together for 
a close fit. They are then thoroughly cleaned 
and cement applied and allowed to dry. The 
ends are then fitted together, more cement 
applied, and the spliced joint put into the 
press and kept under pressure and heat. 

Regardless of the method used to join to- 
gether the belt ends, it is essential that the 
joints be perfectly square with the centerline 
of the belt. 

Correct Belt Tension 

Proper tension on a belt is maintained by 
means of screw type take-ups on small in- 
stallations and by means of suspended coun- 
terweights, gravity take-ups or other auto- 
matic arrangements where the pulley centers 
are long. 

The tension should be just enough to keep 
the belt from slipping on the drive pulley and 
keep sag between idlers to a minimum. 

Too much tension is bad for a belt. It may 
result from the improper maintenance of roll- 
ers, idler pulleys or carriers; excessive tight- 
ening of take-up screws,- too heavy a take-up 
pulley,- loading of the belt beyond that for 



PROPER INSTALLATION MEANS LESS MAINTENANCE 

1 . Use right grade of belt for the expected work and 
for the specific material handled. 

2. Be sure that pulleys are large enough. 

3. Install belts in place carefully.— Do not crease, 
fold, or strain them in any way. 

4. Splice belt ends square with the belt. 

5. Protect belts at loading and transfer points. 

6. Enclose conveyors wherever practical in order to 
shelter them from the weather. 

7. Make sure that the conveyor structure is firm 
enough to prevent vibration. 



164 



INDUSTRIAL CONVEYORS 



which it was calculated; and the shrinkage 
of the belt from exposure to moisture. 

Loading 

Since the principal shock wear on a con- 
veyor belt occurs at the loading point, be 
sure that the feed chute discharges as gently 
and as near belt speed as possible. 

If the material contains large abrasive lumps, 
feed some fines to the belt first to cushion the 
impact of the large heavy pieces. The notch- 
ing of the mouth of the chute or the use of 
a screen chute will permit the finer material 
to drop on the belt first. 

Loading a belt directly over a pulley or 
carrier roller subjects the belt and the rollers 
to considerable pounding. Where such load- 
ing is necessary, special cushioning devices 
like impact idlers or carriers are available. 

See. that proper clearance is maintained be- 
tween the belt and the bottom and tip of 
the chute to prevent any scraping contact. 

Watch also to see that the material being 
conveyed does not get wedged between the 
belt and the chute or other part of the con- 
veyor structure. Trapped lumps can do much 
damage to the belt. 

Protection from trapped lumps may be ob- 
tained in several ways. Brushes or scrapers 
can be used to clean off the belt. Or spill- 
age can be kept off the return side of the 
belt by installing a decking over the latter. 

When skirt boards are used in front of the 
loading chute, see that they do not come in 
contact with the belt. Gaps may be closed 
with rubber strips. 

Making Repairs to Belts 

Belts are specifically designed and con- 
structed for handling various kinds of ma- 
terials. Nevertheless, belt covers and edges 
do get cut, chafed and gouged. 



Good maintenance practice calls for the 
immediate repair of any damage because un- 
attended wounds permit dirt and moisture to 
attack the duck. Furthermore, if the use of 
a damaged belt is continued, the impact and 
the sliding passage of injured areas over 
idlers and pulleys will enlarge the wounds. 
Regular inspection of belts is therefore nec- 
essary. 

A satisfactory way to repair this damage 
is to cut out the damaged spot and vulcanize 
new rubber into the hole. Here again the 
repair can best be done with a vulcanizer 
such as that used for splicing ends. For mak- 
ing repairs in the cover of rubber belts, how- 
ever, small portable electric vulcanizers can 
be used. Complete instructions on their use 
are supplied with the units. 

If however, vulcanizing apparatus is not 
available, repairs to the cover can be made 
in other ways. There are on the market various 
filler and patching materials for use in making 
repairs. These materials include plastic type 
fillers, repair gum, tire dough, repair fabric, 
and so forth. 

One method is to fill the hole with a plastic 
tire dough. Another way is to cut a patch 
from a roll of repair gum and insert it in the 
hole. In either case the loose material around 
the edges of and in the wound should be cut 
away with a knife and the edges evened 
off. Then be sure to clean out all dirt, using 
a wire brush where advisable. When clean 
and dry the wound is filled with the filler or 
repair gum. 

Keep Belts Running Straight 

Belts which have been correctly installed 
on apparatus of good design and which have 
been kept under proper tension should run 
straight. 




165 



PLANT MAINTENANCE MANUAL 



In case a belt does run crooked, the only 
sound thing to do is to find out the real cause 
of the trouble. Under no circumstances should 
one resort to such damaging practices as 
those of trying to straighten the run of the 
belt by increasing the tension, adjusting head 
or tail pulleys when they are already in 
alignment, or by adjusting unequally the take- 
up screws or overloading the suspended ten- 
sion pulley. 

Guide idlers are sometimes used to adjust 
new installations or are incorporated where 
otherwise found necessary. If used, they 
should be inspected for free rolling and to 
see that they do not stick and thus wear 
down the edges of the belt. 

In many installations a slight forward tilt to 
the carriers will help to keep the belt straight. 
Other remedies are to skew troughing rolls 
or use self aligning rollers. 

Some of the causes for belts running 
crooked, and the cures, are as follows: 

1. Lopsided load— Correct feeder chute or 
install self-aligning idlers. 

2. Misalignment of conveyor— Check convey- 
or for correct alignment of supports. Some- 
times head shaft may not be square with 
centerline. 



3. Faulty carrier idlers— Check idlers for lev- 
elness, squareness with conveyor center- 
line, lack of lubrication, faulty bearing, or 
freezing. Correct bad condition. 

4. Edge worn thin— Cut out worn belt and 
splice in new section, or put in new belt. 

5. Faulty splice— Splice must be square with 
the centerline of the belt. If renewing or 
replacing fasteners at joint, square ends 
again. 

6. Insufficient belt contact— If belt is too stiff 
or too thick, run belt slower to carry more 
load or use self-aligning idlers. 

7. Faulty return idlers— Check shafts for 
squareness with run of belt, misalignment 
of supports, or dirty rollers. 

Roller or Idler Care 

Rollers, idler pulleys and belt carriers which 
are clogged with sand or other foreign mat- 
ter may fail to turn, thereby causing the belt 
to rub along the surface. 

Inspect the roller carriers and idler pulleys 
frequently— normally every 30 to 90 days de- 
pending upon the service conditions, the con- 
veying requirements, and the lubricants used. 
See that there is no excessive end play or 
no unusual wear of, or damage to, rollers, 



PRACTICES THAT LOWER OPERATING COSTS 

1. Inspect equipment as frequently as operating 
conditions dictate. 

2. Keep belt clean, and free from oil and grease. 

3. Repair belt wounds immediately. 

4. Keep belts and conveyor supports in proper 
alignment. 

5. Maintain satisfactory belt tension by adjusting 
take-ups as necessary. 

6. Watch belt fasteners. 

7. Lubricate the carrying, returning, and guide roll- 
ers periodically. 

8. Take care of driving machinery and power trans- 
mission mechanisms. 

9. Feed loads on to belt uniformly, carefully and 
gently. 

10. Remove scrap metal pieces from belt by hand or 
by use of magnets or magnetic pulleys. 

11. Prevent spilled material from accumulating on 
rollers. 

12. Operate at speeds that will permit material to 
ride without vibration or rolling. 



166 



INDUSTRIAL CONVEYORS 



brackets and base. Watch for damaged roll- 
ers at feed points. 

Keep rollers free-moving. Periodic lubrica- 
tion should be observed, the time schedule de- 
pending upon the severity of service, the kind 
of roller, and the climatic conditions. Lubricate 
with care because oil and grease are harm- 
ful to most belting materials. Excessive lubri- 
cation should be guarded against, especially 
if the bearings are of the anti-friction types. 

Clean rollers of any caked dirt and con- 
veyed material accumulations under the rollers. 











Belt Conveyors 




ENEMIES 

OF 
BELTING 

ARE: 




SO GUARD AGAINST THEM 



167 



PLANT MAINTENANCE MANUAL 



Storage 



Attention should be paid to the proper 
storage of belts. Since heat, light and air 
promote oxidation of rubber, belts should not 
be stored near steam pipes, radiators, hot air 
registers, or windows. Ordinary room tem- 
peratures are usually satisfactory, except near 



the ceiling or roof. An ideal storage place 
is in a cool, dark cellar, free from moisture, 
heat in summer and frost in winter. 

Spare rubber belts should be left in their 
original package until ready to be used. Keep 
rolls upright. 




OVERHEAD CONVEYOR SYSTEMS 



One form of overhead conveyor comprises 
an elevated rail or track along which run 
trolleys, connected together in an endless 
chain arrangement. These trolley systems may 
either pull loads or carry them in suspension. 
In the first case, trucks or racks, for instance, 
are attached to the chain and are pulled 
along the floor directly beneath the overhead 
track. In the second case the carriers are 



suspended from the trolley. The carriers may 
be hooks, trays, racks, buckets and the like, 
depending upon the sort of goods or mate- 
rials being conveyed. 

The chain and trolleys are the chief ele- 
ments of the system. They are the moving parts 
that require periodic inspection for lubrica- 
tion and alignment between the chain, track, 
and the sprockets. Chains and sprockets that 




168 



INDUSTRIAL CONVEYORS 



are "out of line" are subject to excessive 
wear. The chapter on transmission chains in- 
cludes information on conveyor chains as 
well, and additional data can be obtained 
therefrom. 

The chains, for instance, articulate at the 
pin bearings and connections and thus re- 
quire proper lubrication. The trolley bearings 
should not be neglected either. In some de- 
signs automatic lubrications are available. 

Sometimes overhead chain conveyors pass 
through dryers or ovens in which the tem- 
perature rises to several hundred degrees. 



In such installations great care should be 
shown in providing for proper lubrication. Lu- 
bricqnts for practically any installation— low, 
normal or high temperature— are available. 
Lubrication specialists can offer recommenda- 
tions for the problems presented by any usual 
or unusual installations. 

Guards, either stationary or attached to the 
conveyor, should be used where dirt or grease 
might fall on the products being conveyed. 
Similar protection should be accorded con- 
veyors when they pass through spray booths, 
since paint and water are detrimental to 
good operation. 




169 



PLANT MAINTENANCE MANUAL 



TRAMRAIL AND MONORAIL CONVEYORS 



Another similar form of overhead mate- 
rials handling equipment is that in which the 
elevated monorail or tramrail system carries 
hand - chain or electric hoists. The trolley- 
hoists are moved manually or by electric op- 
eration, instead of being driven by endless 
chains. These systems are commonly classed 
as overhead hoists and cranes; nevertheless 



they do perform considerable conveying 
duties as well in many applications. 

In regard to the hoisting equipment in- 
volved, instructions on the care and main- 
tenance of chain and electric hoists are given 
in the chapter on them. 

One convenient inspection schedule for 
overhead rail conveyors is as follows: 



INSPECTION SCHEDULE 

ONCE A MONTH 

Trolleys — Inspect for lack of, or excessive, lubrica- 
tion. Check wheels for wear. 
Cross-Overs, Switches, etc. — Check for correct 

alignment and clearances. 
Oil and Grease Fittings — Add lubricant as required. 

EVERY THREE MONTHS 

Roller Chain Drives — Check for tightness and align- 
ment. 

Running Gear — Inspect shafts and couplings for 
loose bolts and screws. Lubricate. 

Trolley Wheel Bearings — Check and lubricate. 

Runways — Check supports and hangers for loose 
bolts, nuts and other fasteners. 
Examine track for wear. 

EVERY SIX MONTHS 

Entire Equipment — Clean thoroughly, removing ac- 
cumulated dirt and debris. Clean rusty spots, and 
paint. 



PNEUMATIC CONVEYORS 



One kind of pneumatic conveyor is a tube 
system in which air power propels a cylin- 
drical or oval-shaped container that fits 
tightly in the tube. This method is used pri- 
marily for the movement of factory orders, 
job and time tickets, requisitions, drawings, 
and small tools and parts. 

Pneumatic tube installations may be either 
suction or pressure type, or a combination of 
both. In addition to the tubing, principal parts 
are the power unit, and the dispatching and 
receiving terminals. 

Another form of pneumatic conveyor is 
that which moves bulk goods by suction or 
pressure. The materials must be loose, fine, 
and granular and not very dense— such as 
cement, grain, and other dry pulverized prod- 
ucts, even crushed coal. 

In the suction type, a partial vacuum cre- 
ated by an exhauster or blower generates an 



air velocity which draws the air and material 
through the intake nozzle and conveyor hose 
line and conveys them to the discharge. 

In the pressure type, air pressure rather 
than a vacuum is the moving agent. The pres- 
sure may come from the exhaust side of a 
blower, for example. 

In another variation, the pressure pump sys- 
tem, the material is drawn into the pump and 
advanced by an impeller screw. Just beyond 
the pump screw section, air is injected. The 
air expands the material, making it fluid so 
that it can be moved through the conveyor 
line by mechanical power. 

The essential parts of a pneumatic installa- 
tion which are subject to inspection and main- 
tenance attention are exhausters, blowers, re- 
ceivers, filters, air locks, separators, valves, 
hose, duct, compressors, vacuum pumps, and 
so forth. 



170 



INDUSTRIAL CONVEYORS 




Bucket Elevator 



Continuous Flow Conveyor 




171 



PLANT MAINTENANCE MANUAL 



CONTINUOUS FLOW CONVEYORS 

Another continuous carrier is the flight con- 
veyor for the en masse movement of pulver- 
ized, granular, small lump, or flaky products. 

The flights, which travel in an enclosed 
casing, may be flat, peaked, or skeleton "U" 
in shape and are linked together by chain 
or rod sections. 

Essential parts of these conveyors that re- 
quire maintenance are the flights, scrapers, 
chain belts or links, locking pins, drive sprock- 
ets, tail wheels, inspection doors, feeding 
devices and discharge arrangements. 

BUCKET ELEVATORS 

Endless belts or chains to which buckets 
are attached are used for conveying bulk 
materials in a vertical or other steeply in- 
clined direction. The buckets may be spaced 
or set continuously. 

The maintenance of these elevators is gen- 
erally the same as for the corresponding 
conveyors. 



Materials used in the construction of ele- 
vator belts, for instance, are the same as in 
conveyor belts, except that the former usually 
have more plies than conveyor belts of the 
same width. 

Because of the buckets and the housing, 
crooked running of elevator belts, one cause 
of which is uneven loads, can be damaging. 
If feeding is by spout, therefore, check the 
feed to see that it centers on the buckets. 

Loosening of bucket bolts can be trouble- 
some,- so inspect the bucket connections pe- 
riodically. 

Material spilled between the belt and the 
boot pulley, too, can be harmful. 

Maintaining the proper tension is very im- 
portant in belt elevators as it is in belt con- 
veyors. 

As in all preventive maintenance, constant 
vigilance pays off with low-cost conveying 
operations. So inspect elevators at least once 
a week. Check all joints and clearances. 
Tighten loose bolts and replace worn buck- 
ets and fasteners. 



172 




CHAPTER 17 



PORTABLE ELEVATORS AND CONVEYORS 



Many kinds of portable conveyors and ele- 
vators are used in handling materials in the 
modern mill and factory. While there is a 
distinction between conveyors and elevators, 
most portable conveyors also elevate the 
goods they convey. In some cases, therefore, 
these devices go under the combination title 
of conveyor-elevators. 

These portable forms of materials handling 
equipment go under a variety of names which 
describe their more immediate purposes. They 
are called, for instance, stackers, lifters, tiering 
machines, hoists, loaders, piling machines, ele- 
vating tables and the like. Portable cranes and 
hand and lift trucks may also be considered 
in this group. Furthermore, industrial power 
trucks, which are covered in another chapter, 
are also members of this materials handling 
family. 

General Maintenance 

Portable equipment is often subjected to 
more abuse than fixed systems; so good care 
and proper maintenance are important in get- 
ting the most out of the equipment. 

Regardless of the many kinds of portable 
devices, there are certain fundamental prac- 
tices that apply to the maintenance of all. One 
common abuse that needs correction in many 
plants is improper or inadequate lubrication. 
Another weakness is the failure to make re- 
pairs or replace worn or damaged parts. 



Periodic inspections of each piece of equip- 
ment and all its parts by mechanics or other 
qualified persons, then, is essential. Suitable 
reports or records of the results of those in- 
spections will also be of considerable help. 
A check list, for instance, is an advantageous 
form for procedure and of record for that 
information. 

But of even more concern is the taking of 
proper corrective action to remedy any trou- 
bles that may have developed and need at- 
tention. 

Detailed procedures for maintenance, how- 
ever, vary according to the kind and make of 
apparatus. In all cases, therefore, be sure to 
follow the manufacturer's instructions as to 
what to do and when to do it in caring 
for, lubricating and otherwise maintaining its 
products. 

To present some concrete maintenance prac- 
tices, therefore, it has been necessary to select 
a few representative portable conveyors and 
elevators and show in detail the recommended 
procedures for that particular piece of equip- 
ment. But although these instructions are spe- 
cific to a certain machine, many of the steps 
taken could apply to many other devices of a 
similar nature. 

PORTABLE CONVEYORS 

Most types of conveyors — belt, bucket, 
apron, screw, pneumatic, roller, wheel, en 



173 



PLANT MAINTENANCE MANUAL 



masse and bulk flow, to name a few — are 
made in portable varieties as well as for fixed 
installations. Although these portable units 
come in such a wide range of forms, only a 
relatively few basic types can be considered 
here. 

Portable belt conveyors, for example, are a 
widely used kind of materials handling equip- 
ment. They are commonly used for handling 
bulk materials and packaged or unit goods, 
for loading and unloading cars, trucks and 
other carriers, and other varied purposes. 
Portable belt conveyors do not differ funda- 
mentally from the fixed kind, except that they 
are provided with wheels or casters for por- 
tability. 

Self-contained power units consist of the 
framework; the driving power, which is usually 
an electric motor or a gasoline engine; a 
drive pulley at one end and an idler pulley at 
the other,- and idler rollers or plates, or a com- 
bination of both, which support the belt on 
which goods are moved. Transmission of 
power from the motor to the drive pulley is 
accomplished by means of gears, flat or V 
belts, chains, or speed reducers. Sometimes 
gear motors drive the pulleys directly. 

For carrying goods up steep inclines, the 
belts may have cleats attached to them. Belts, 
which are usually rubber-covered duck or 
canvas, may be flat or troughed. 

BELT CONVEYORS 

Portable belt conveyors are ruggedly con- 
structed to give trouble-free service and are 
thoroughly inspected before leaving the fac- 
tory. 

Nevertheless, they should receive periodic 
inspections and maintenance attention. Main- 
tenance should include examination of the 
drive motors and power transmission, of pulleys 
and rollers and their bearings, of conveyor 
belts, and correct lubrication. Conveyors that 
elevate goods also have various rigs and 
mechanisms for raising them, the parts of which 
should not be overlooked. 

Motor Care 

For the care of the particular motor installed 
in the conveyor unit, follow the instructions 
supplied by the manufacturer. 

Proper lubrication of the motor is important, 
but use only recommended lubricants. Observe 
instructions and specifications shown on the 
lubrication instruction plate. 

If, for example, the motor is of a gearhead 
type, a representative procedure is as follows: 

Keep gear case oil at right level. The oil 
level may be checked by removing the oil 



level plugs. So inspect the gear case oil from 
time to time to see that it is at the proper 
height to lubricate the gears and bearings. If 
oil is low, add enough to bring it back to the 
right amount. 

Do not check the oil level or add oil to the 
gear case when motor is running. 

The gear case should be drained and refilled 
periodically— a good interval is every three to 
six months, depending upon the use. Another 
recommended practice is to drain and fill the 
case after 750 hours of normal daily use, or 
after 500 hours if the operation is continuous 
or temperatures are excessively high. 

It is often well to lubricate motor shaft bear- 
ings every three months, if necessary. 

The power transmission equipment should 
also be inspected periodically, and worn or 
damaged belts or chains, etc., should be re- 
paired or replaced. 

Pulleys and Rollers or Carriers 

In this same representative conveyor, the 
head and tail pulleys have sealed type bear- 
ings with pressure lubrication fittings. Since 
these bearings are grease-packed at the fac- 
tory, they should not require, under normal 
service, lubrication for six months or so. In 
order not to damage the seals when lubricat- 
ing with a grease gun, do not use too much 
pressure. Lubricate them sparingly with a good 
grade of ball bearing grease. Be sure to wipe 
off the grease fitting before attaching gun. 

A lubrication chart of a representative make 
of belt conveyor is presented to serve as an 
example of specific schedules for, and kinds 
of, lubrication. In all cases follow instructions 
which accompany the particular conveyor or 
special installation. 

Inspect idler rollers or carriers periodically 
for free turning because jammed rollers wear 
out belts. Lubrication schedules for oiling the 
bearings of these rollers are shown on the 
above mentioned chart. 

Conveyor Belts 

Keep belts clean and dry, and protect them 
from oil and grease. A belt that has stretched 
should be taken up before it is damaged fur- 
ther by slippage. 

The tension on a belt should be sufficiently 
tight to prevent slippage over pulleys; yet it 
should not be so tight as to cause excessive 
strain and wear on the bearings of the pulley. 

To adjust a belt for correct tension, follow 
the manufacturer's instructions for that partic- 
ular type of conveyor. Take up is usually done 
at the tail end of the conveyor unless the drive 
is at that end. Drives are usually at the head 
end. 



174 



PORTABLE ELEVATORS AND CONVEYORS 













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175 



PLANT MAINTENANCE MANUAL 




One specific type of portable belt conveyor 
requires the following suggested procedures: 

Where a tail idler pulley has a screw type 
take-up, for instance, turn the adjustment 
screws equally to take up the slack or relieve 
the tension, whichever is necessary. 

Run the belt in reverse, which is toward the 
tail end, and check slippage at the drive pulley. 

Tracking or Training Belts 

It is also important that belts track properly 
in the center of the pulleys in order not to 
subject the belt to unnecessary wear from 
guide rollers along the edges. 

One method of making these adjustments for 
tracking of newly-installed belt on a represen- 
tative conveyor is as follows: 

Run the belt first in reverse (toward tail pul- 
ley) for the adjustment of the tail idler pulley 
and head idler roller. In adjustments of the 
screw type, tighten adjustment screw on side 
of tail idler pulley toward which the belt tends 
to travel until the belt is running in center 
of pulley. 

Adjust the head idler roller so that the belt 
centers on it. If rollers have adjustment plates, 
move the plates to the right or left, as the need 
may be to center the belt on the drive pulley. 

Next, run the belt forward (toward the head 
end) for adjusting the idler rollers or carriers. 



If they have adjustment plates, the latter are 
moved to the right or left for the desired 
correction. 

These adjustments are made while the belt 
is unloaded. 

For another conveyor, the following is rec- 
ommended: 

See that all pulleys and carriers are accur- 
ately set at right angles to travel of belt. Since 
carriers are designed with a slight tilt in the 
direction of travel of belt, the belt will track 
without further adjustment. 

If the belt persists in running to one side, 
begin adjusting one or two carriers back of 
point where belt starts to stray from the straight 
path. Tap the carriers slightly with the direction 
of travel. The effect is to direct the axis of 
travel toward the center. 

ROLLER CONVEYORS 

Another common form of portable conveyor 
is that on which loads move along rollers or 
wheels. These are usually short sections of 
standard conveyors mounted on bases with 
wheels or casters to make them portable. 
Conveyor sections may be straight or curved. 

These conveyors may have a series of in- 
dividual rollers that run across the width of 
the conveyor or a series of double rollers on 
the same cross-shatt in the framework. Rollers 



176 



PORTABLE ELEVATORS AND CONVEYORS 




177 



PLANT MAINTENANCE MANUAL 



may be of various shapes— cylindrical, con- 
cave, conical or tapered, or other special 
rolling shapes. 

Another kind of roller conveyor is made up 
of a series of small wheels uniformly spaced 
within the framed section. Several wheels may 
be attached to a shaft running crosswise to 
the length, or wheels may be mounted on 
longitudinal runners. The wheels revolve on 
fixed bearings. 

Bearing Lubrication 

These rollers and wheels have free-rolling 
ball bearings which may or may not have dust 
seals or pressure lubrication. Under normal 
conditions of moisture in indoor installations 
where there is considerable dust or dirt pres- 
ent, the lubrication of the bearings may not 
be advisable. 

However, in outdoor installations and under 
wet or high moisture conditions, frequent lub- 
rication of open type ball bearings with light 
machine oil is recommended. 

The casters or wheels on the stands should 
be maintained in much the same manner as 
those on the portable bases of belt conveyors. 

PORTABLE ELEVATORS 

Portable elevators often go under names 
more descriptive of the duties they perform, 
such as stackers, tiering machines, elevating 



tables, lifters, and so forth. There are many 
variations in design and construction. 

Since these elevators differ in form and 
details, it is necessary to follow completely 
manufacturers' instructions for their care and 
maintenance. 

One representative kind of portable ele- 
vator is the platform hoist type. It is used for 
stacking and tiering and can be adapted to 
handling many special products and loads like 
tin plate, pallets, rolls of paper, pans, drums, 
etc. 

It consists of a framework of structural 
shapes such as channels, angles and bars 
commonly welded together. A platform is 
raised along the framework by hand, or by 
electric or hydraulic means. 

Hinging of frames enables their passage 
under overhead obstructions, roof members, or 
through doors. Some frames are telescopic 
and these too may be hinged. Bracing, of 
course, depends upon the height and width of 
the structure. 

For handling very heavy loads, four post 
elevators are available. These too may have 
hinged or telescopic frames. 

These elevators are completely assembled, 
tested and inspected at the factory before 
shipment. Sometimes, however, it is necessary 
to dismantle an elevator partially and detach 
the hoisting cable from the platform. 




78 



PORTABLE ELEVATORS AND CONVEYORS 




179 



PLANT MAINTENANCE MANUAL 



LINE 
SWITCH 









UPPER LIMIT 
SWITCH 



UPPER 
STOP PLATE 



D 




LOWER 
STOP PLATE 



ACROSS THE 
LINE STARTER, 
.WITH THERMAL 
OVERLOAO 
PROTECTION 






CABLE 
CONTROL 



1^ 

W CABLE 6UARO 



LOWER SHEAVE 
ASSEMBLY 



PUSH BUTTON 
CONTROL 



Putting Into Service 

Check with manufacturer's drawings to see 
that any necessary reassembly or erection work 
is done correctly and satisfactorily. 

Before putting the elevator into service, see 
that it is free from all debris and that the plat- 
form is clear of all obstructions. Check hoisting 
mechanisms. Then run elevator up and down 
a few times to see that everything is working 
right. 

When electrically operated, for instance, 
check the wiring diagram for that particular 
elevator and for the assembly of the cable 
or the push button control, which are the two 
forms of electric controls. 

A flexible cable conducts the current to the 
elevator. In the case of a 3-phase current, 
three wires carry it while the fourth wire is 
used to ground the elevator structure in case 
of a short circuit. Because of the peculiarity 
of the 3-phase wiring, it may be necessary to 
change the electrical connections when con- 
necting up the elevator's line to the customer's 
service in order to have the motor rotate in 
the right direction. 

To correct the direction of motor rotation, 
interchange any two wires running from the 
current source to the main switch. 



Cable Control 

In checking a cable control elevator, see 
that the elevator stops automatically at the 
extreme top and bottom of travel along the 
frame without the operator turning control 
handle. Check button "stop" devices for se- 
curity. 

Chain controls may be supplied in place of 
cable control in some applications. 

On push button control elevators, limit 
switches stop the movement at the extremes of 
platform travel. These devices should trip the 
current even if the operator has failed to shut 
it off. 

Motors 

In electrically operated elevators, the motors 
do not require any special attention other than 
lubrication from time to time. Lubrication of 
elevators is covered in another part of this 
chapter. 

Lubrication of brake discs is neither nec- 
essary nor desirable. Motor brakes do not 
ordinarily require brake spring tension ad- 
justment further than that originally provided. 
Adjustment can, however, be made for spring 
tension and torque. Prolonged use wears the 
brake lining slightly. If that occurs, the air gap 
may be adjusted to compensate for the wear. 



180 



PORTABLE ELEVATORS AND CONVEYORS 



Hydraulic Systems 

Hoisting power of elevators or lift trucks 
may be through hydraulic means in which a 
hand pump or motor driven hydraulic pump is 
used. In maintaining a hydraulic unit, always 
follow the manufacturer's instructions. 

Representative of hydraulic operation is the 
following maintenance procedure for a typical 
high lift truck. The pump oil reservoir is orig- 
inally filled with hydraulic oil by the manufac- 
turer. For a subsequent refilling, use any good 
grade of oil recommended by the manufacturer. 

To add oil to the hydraulic system remove 
the pipe plug of the pump oil reservoir and fill 
reservoir up to the marker or level designated 
by the manufacturer's instructions. Be sure to 
strain all oil before adding it to the system. 

If desired, the manufacturer will supply suit- 
able oil. 

When the pump loses its efficiency, it is usu- 
ally best to return it to the manufacturer. In 
most installations of this sort the pump is easily 
detached by removing the hose connection 
and the bolts and other fasteners which hold 
the pump in place. 



Cable Replacement 

As previously stated there are many adap- 
tations of the basic platform elevator idea, 
and the manufacturer's recommendations for 
the care and maintenance of his equipment 
should be observed in each case. For the sake 
of illustration, however, a specific application 
is given below. 

When it is necessary to install a new cable, 
note carefully the roping arrangement through 
the several sheaves in order that correct re- 
placement will be made. 

In ordering a cable replacement determine 
the overall length and diameter of the old 
cable and advise the manufacturer of the ser- 
ial number of the elevator. 

Correct fastening of the ends of the cable 
to the drum and to the platform or elevator 
anchor is most essential. If the cable is not 
supplied with finished ends, the following is a 
typical procedure that may be followed. 

Cable Clips 

Be sure to install cable clips properly. 
Cable clips should be attached so that the 



II 
















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a 






OfT 


















fl ° 




I 












II 


Ife^- 












\S2l % 




HYDRAULIC PUMP 



HOISTING 
CABLE 



SADDLE ON 
THIS SIDE 




LOAD CARRYING 
SIDE OF CABLE 

IDLE END 
OF CABLE 
"1 

METAL 
TIP 
EXPANSION 
BALL INSIDE 



BOLTS 

[THIMBLE FOR 
"ATTACHING TO 
PLATFORM OR 
CABLE ANCHOR 
ON ELEVATOR 
STRUCTURE 




FOR 

ORUM 

INSERTION 



Cable Care 

Standard flexible preformed hoisTing cable 
of plow steel is used on most elevators. 

There are several roping arrangements. In 
one set-up the cable is roped from the drum 
over the top sheave of the elevator and an- 
chored on the platform. Or the cable from the 
drum may loop over the top sheave of the 
elevator and around a sheave on the platform, 
and then be anchored to the elevator struc- 
ture. Or the elevator cable may loop several 
sheaves on top and on the platform. 



saddle is on the load carrying or live side 
with the bolt going around the idle short side. 
Spacing of clips should be six times the rope 
diameter. Tighten nuts equally and securely 
before, and again after, the load is applied. 
Retighten clips again after an hour or two of 
service. 

Check cable for condition and clips for 
tightness frequently. 

Anchor End 

To form the anchor end, loop cable end 
around the thimble guard and fasten loose 



181 



PLANT MAINTENANCE MANUAL 



LUBRICATION SCHEDULES 

Suggested lubrication practices of represen- 
tative portable elevators are shown here. One 
is hand operated and the other is electric- 
motor operated. Always follow manufacturer's 
recommendations for individual elevators. 

A-2 



ELECTRIC MOTOR 

OPERATED 

PORTABLE ELEVATOR 




A-3 



182 



PORTABLE ELEVATORS AND CONVEYORS 



HAND-OPERATED PORTABLE ELEVATOR 



A-5 




183 



PLANT MAINTENANCE MANUAL 



end to load carrying side of the cable with 
cable clips. 

To prevent cable end from slipping through 
the cable clips, bulge one end of the cable. 
Wrap seizing wire about one-half inch from 
short end. Cut core out of cable close to 
seizing. Fit a metal cap over the strands at the 
end of the cable. 

Between the cap and seizing wire, spread 
strands of the cable and insert steel expan- 
sion ball. Then dip entire end of cable in a 
tinning pot and tin it to seizing. 




Plug For Drum Insertion 

Prepare the other end of the cable for 
insertion in the drum. 

Heat some pure zinc to 800 to 875 deg. F. 
To test temperature of the molten zinc, use a 
soft pine splinter. If the splinter flames, the 
zinc is too hot. If the zinc sticks to the splinter, 




the former is too cold. When the zinc is at the 
right temperature, it will char the splinter slight- 
ly. Warm up the mold for the plug also. 
Other steps are as follows: 

1. Apply fine seizing wire, about ten turns, 
one inch from the end of the cable. 

2. Untwist strands at the end and remove 
the rope core. 

3. Broom out wire and clean in benzine, 
naphtha or other suitable solvent. Exercise 
care when using inflammable cleaners. 

4. Dip in solution or half commercial mu- 
riatic acid and half water for 25 to 30 minutes. 

5. Wash cable end in boiling water. Test 
temperature of molten zinc as described above. 

6. Place cable in warmed mold, and pour 
molten zinc in slowly. Sal ammoniac crystals 
on the wire will help the zinc to flow into 
small crevices. 




Replacements 

In ordering replacements from the manufac- 
turer of the elevator, give serial number of the 
equipment and complete details of the part or 
parts desired. 



184 




CHAPTER J 8 



INDUSTRIAL POWER TRUCKS 



Every mill and factory is a materials han- 
dling system in which goods of all kinds must 
be moved horizontally, raised, lowered, piled 
and unpiled, and loaded and unloaded. Some 
authorities go as far as to estimate that from 
one quarter to one third of the time spent in 
manufacturing industrial products is taken up 
in moving them. 

Mobile materials handling equipment, there- 
fore, plays an important role in a modern plant 
because industrial power trucks can perform a 
variety of handling duties with manpower sav- 
ing dispatch. A most practical application lies 
in the field of mechanical handling where the 
movements of materials are intermittent rather 
than continuous along a line of travel, or be- 
tween fixed or varying points in a plant and 
its adjoining area. 

These mobile systems comprise tractor-trailer 
haulage and trucking equipment of the plat- 
form, skid, and pallet types. A basic feature of 
them, with the possible exception of the plat- 
form truck, is the handling of materials in unit 
loads. 

Conditions which influence the selection of 
the power-truck system best suited to the needs 
of a plant are such factors as the distances of 
travel, the tons to be carried per trip, and the 
numbers of trips per work shift. Also, if goods 
are to be stacked or tiered for storage, the 
number and the height of the tiering opera- 
tions must be taken into account. 



From the basic types of power trucks de- 
scribed and illustrated in the section on 
"Handling Systems," many special systems have 
been developed to handle goods and pack- 
ages of shapes and sizes not readily adapted 
to standard pallet, skid, or trailer treatment, 
yet possesing unit load characteristics. These 
specials include scoop trucks for shoveling, 
lifting, and dumping bulk goods and ram 
trucks for carrying wire and strip in coils. 
There are also roll-handling trucks for lifting 
and moving newsprint and other papers and 
special trucks for ladles, reels, and malleable 
pots. Some trucks may have swinging booms 
for crane operations and others have articu- 
lated action for handling packages of large 
metal sheets. 

Mobile equipment may also be supplied for 
such plant services as fire fighting, machine 
lubrication, electrical repair work, and lighting 
fixture maintenance. 

Manufacturers of industrial power trucks 
will supply complete and constructive informa- 
tion on all kinds of equipment. 
Motive Power 

Motive power for industrial trucks is of the 
following kinds: 

a. Electric— in which storage batteries supply 
the power. 

b. Gas— in which gas engines power the trucks. 

c. Gas-Electric— in which the power supply 
is engine generated. 



185 



PLANT MAINTENANCE MANUAL 



ECONOMICAL OPERATION 

For the economic operation of mobile ma- 
terials handling equipment, be sure to pay 
attention to floor gnd building conditions. 

Floors should be hard and smooth, such as 
those provided by cement, asphalt, wood block 
or brick constructions. These pavements must 
be maintained constantly in order that they do 
not become rough or uneven, and thereby 
increase tractive resistance. 

Grades and ramps should be held to the 
practical minimum. To ascend a grade of 2 
per cent, for example, will require double 
the power to pull a given load along an even, 
level floor. A grade of 10 per cent should be 
considered the maximum. 

Plainly marked aisles are- a great help in 
truck operations. Adequate ventilation and 
good lighting are also important aids, espe- 
cially in work or storage areas. 

Clearances 

Proper clearances should be provided in all 
working a r eas so that power trucks can be 
run and turned easily. 

All doors and aisles should be large enough 
to permit the largest trucks and loads to be 
moved through and along them conveniently. 
If aisles are long, widened areas should be 
provided every 50 to 100 feet to permit loaded 
trucks to pass each other. 

For faster and easier opening and closing 
of doors, they should be equipped with elec- 



tric opening devices actuated by means of 
overhead pull rope, push-button switch con- 
veniently located for the truck driver to reach, 
photo-electric cells, or other apparatus. 

Clearances at loading areas, in front of 
elevators, on loading docks, and where aisles 
intersect and end should be sufficient for easy 
right-angle turns. 

Training Operators 

In no field is the application of that old 
saying that "practice makes perfect" more 
pertinent than in the operation of industrial 
power trucks. New operators, therefore, should 
be given sufficient training and practice in 
turning, elevating, tiering, tilting and the other 
materials handling features that can be per- 
formed by power trucks. 

Operators should be taught to know the 
weight and tip capacities of the trucks he 
drives and that the balancing point lies over 
the front drive wheels. He should learn the 
best speeds of travel for the machine and the 
space required for stopping. He should be 
acquainted with the commodities handled. 

Speed of Operations 

Speeds at which industrial power trucks 
commonly operate lie in the range of from 
90 to 500 feet per minute. Although trucks are 
designed for higher speeds, it is not well, from 
the standpoints of safety and cost, to exceed 
the top limit, except on long hauls or clear 
roads or aisles. 




186 



INDUSTRIAL POWER TRUCKS 




187 



PLANT MAINTENANCE MANUAL 



HANDLING SYSTEMS 



The several industrial power-truck systems are as follows: 



TRACTOR-TRAILERS: This system is a haul- 
age proposition in which the tractor supplies 
the motive power and the trailers carry the 
loads. In itself, it has no means for loading or 
unloading the materials it transports. Its major 
use is in the movement of large amounts of 
goods over relatively long distances. 




MOTORIZED HAND TRUCKS: Motorized 
hand-lift trucks are made to handle pallets 
and skids. They supplement standard skid and 
pallet trucks and are used advantageously in 
tight spaces and on weak decks which would 
not hold the heavier power trucks. These units 
only move, not tier, materials but are self- 
loading. 





PLATFORM TRUCKS: These trucks are used 
for haulage work. Their principal industrial 
application is in plants which have cranes 
since the trucks have no provisions for loading 
or unloading themselves. They are very useful 
for moving odd pieces. 



LOW-LIFT TRUCKS-SKID: These trucks were 
the first, historically, to be self loading and 
unloading. They can pick up, move, and set 
down goods mounted on skid platforms or in 
skid bins. Except for tiering, manual handling 
of materials is eliminated. 




188 



INDUSTRIAL POWER TRUCKS 



HIGH-LIFT TRUCKS-SKID: In addition to its 
ability to load and unload itself, similar to that 
of the low-lift truck, this type permits the tier- 
ing of materials on skids one above the other 
to increase storage capacity. 





FORK TRUCKS - PALLET: This principle of 
operation is the same as that of the high-lift 
skid system. But instead of a skid platform, a 
forking device is used to pick up goods loaded 
on pallets, or boxed or crated items provided 
with batten strips. Rolls, bales and barrels can 
be handled without pallets. 






WATCH FLOOR CONDITIONS 

#7 Mark aisles plainly. 

pr Maintain aisle surfaces in good condition. 
Keep floors and runways as level as possible 
Hold grades to the lowest practical minimum 




PLANT MAINTENANCE MANUAL 




HINTS ON GOOD OPERATION 



A properly loaded truck is easier and safer to move and un- 
load. Pros and cons of good operation of trucks are as follows: 

A. Approach danger points slowly — Do Not ignore and break traffic rules. 
B. Pick up loads squarely — Never load trucks carelessly and improperly. 

C. Carry moving loads as low as possible — 

Don't overlook proper balance and alignment of load. 

D. Start and stop slowly — Never make sudden stops and jerky starts. 



190 



INDUSTRIAL POWER TRUCKS 



MAINTENANCE 

If diligently adhered to, regular care and 
maintenance of truck equipment will produce 
better results in the end than the making of 
irregular and emergency repairs only when 
necessary. 

Even if this practice may be more expensive 
in labor, it definitely saves in the costs of 
parts and materials. It also saves the cost of 
doing the work by hand while the truck is out 
of service at unscheduled times. Scheduled 
inspections and servicing require that provision 
be made in planning plant truck movements so 
that any short periods of "time out" for a truck 
undergoing shop work will not interfere too 
much with the overall operations of the truck 
fleet. 



Maintenance Program 

A careful maintenance program should be 
organized. It should include periodic inspec- 
tions, regular lubrications, and scheduled serv- 
icing and overhaul. 

Suitable records should be kept on all main- 
tenance work and service troubles and prob- 
lems. Machine records should carry the results 
of inspections of tires, brakes, steering mech- 
anisms; the dates of lubrications and overhauls; 
and the materials and labor used in making 
repairs. 

All responsibility for truck maintenance 
should be centralized in a single department. 
In fact it is often good practice to hold all 
trucks in a single pool and make departments 
requisition them. The setting up of a central 



TIRE SAVING TIPS 





Watch out for metal 
chips and broken glass. 



Stay away from curbs 
and obstructions. 




Avoid cracks and 
depressions in floor. 



Keep clear of oil 
and grease puddles. 



191 



PLANT MAINTENANCE MANUAL 

truck maintenance shop makes the work of 
overhaul and servicing much easier. 

Periodic Checks 

Once a week, or at least once a month, 
as determined by operating conditions, check 
the following: 

Tires, for embedded metal particles. 

Wheel and axle alignment. 

Steering mechanisms and controls. 

Parts, bolts, nuts for looseness or breaks. 

Brakes, clutches, belts, and other friction 
parts. 

Each truck should be checked over com- 
pletely every six months, or more often if 
service conditions demand it. 

At least once a year all bearings and con- 
tacts, electrical and mechanical, should be 
checked. 

Specific practices differ somewhat with re- 



spect to whether the equipment is electric- 
battery or gas-engine operated. These are 
taken up later. 

LUBRICATION 

It is important that trucks be sufficiently lu- 
bricated at all times. So lubricate them regu- 
larly in accordance with manufacturer's rec- 
ommendations as to grades of oil and grease 
as well as frequency. The type of service gov- 
erns the frequency of lubrication. A chart or 
check list is of considerable aid in proper 
lubrication and in being sure that no grease 
fittings are missed. 

Grease steering linkage every week. Check 
oil level in gear housing every month and 
change oil at least every six months. 

In gas-engine trucks, check and change 
oil in crankcase, transmission, and drive axle 
and replace oil filter elements as recom- 
mended in the manufacturer's instructions. 






^Wf^ W.lliUi/e^ 



©■'"■®l 



INDUSTRIAL POWER TRUCKS 



Checking Gas Engine Trucks 



The general inspections and checks already 
given apply to trucks regardless of their mo- 



tive power. Some specific checks of impor- 
tance to gas-engined trucks are the following: 



WHAT TO CHECK 


WHAT TO DO AND 
HOW OFTEN 


Clutch action 
Crankcase oil level 
Engine oil pressure 
Generator charging 

rate 
Radiator 


Check daily. 


Carburetor, ignition, 
exhaust 


Check and adjust at first 
sign of poor function- 
ing. 


Hydraulic system 


Check oil supply at high 

lift daily. 
Adjust, clean, and fill at 

least once a month. 


Radiator core 
and engine 
compartment 


Blow out with com- 
pressed air: 

Where operations are 
in atmosphere la- 
den with dust, lint 
or oil — Clean 
weekly. 
In extreme cases- 
Clean once a day. 


Gasoline and 
oil filter 


Inspect and clean: 

If in clean condition 

— once a week. 
If moderately dirty — 

every three days. 
If extremely dirty and 

dusty — daily or 

once each shift. 


Outside of truck 
and engine 


Clean once a month. 




193 



PLANT MAINTENANCE MANUAL 



Maintenance Schedule for Battery Trucks 

Here is a suggested schedule for maintain- The items listed should be modified lo meet 
ing electric trucks and their storage batteries. individual manufacturer's recommendations. 



HOW OFTEN 


WHAT TO DO 


EVERY 
DAY 


Change or recharge truck bat- 
teries. 

Keep record of use of truck. 


EVERY 
WEEK 


Check water in batteries. 

Check and record specific grav- 
ity of electrolyte, unless 
otherwise advised by the 
manufacturer. 

Wipe off dirt and moisture. 

Check and operate all electrical 
controls. 


EVERY 
MONTH 


Inspect hydraulic or lift system 
and adjust, clean, and fill 
system. 

Clean batteries and compart- 
ments thoroughly, using 
compressed air or steam jet 
to loosen dirt. 


EVERY 
TWO 
MONTHS 


Check oil in all power units. 


TWO 

OR THREE 
TIMES 
A YEAR 


Inspect and blow out motors. 

Inspect commutator and brush- 
es. To do so, remove dust 
covers from motor. 





ipSB® ^UpiL. 



194 



INDUSTRIAL POWER TRUCKS 



BRUSHES AND COMMUTATOR 

An accumulation of carbon dust may cause 
damage. When inspecting motors, see that 
brush holders are in proper position and that 
tension springs are holding the brushes firmly 
in place. Brushes should have at least 60 per 
cent of the surface bearing, and should be 



replaced when worn so that they cannot be 
properly fitted. 

Check commutator for cleanliness and 
smoothness. For cleaning use fine sandpaper 
—not emery cloth. Remove all grit from the 
slots between the commutator bars. Make sure 
that pigtail binding screws are tight and that 
pigtails do not touch any part of motor. 




CARE OF STORAGE BATTERIES 



Preventive maintenance of batteries begins 
with the correct application of the original in- 
stallation and includes correct operating pro- 
cedures. Reference to manufacturers' bulle- 
tins and instructions on the application .oper- 
ation, and maintenance of batteries is es- 
sential. 

Be sure that the batteries are of sufficient 
capacity to operate the trucks normally for a 
full 8-hour shift. Boost charging should not 
be practiced as a regular substitute for bat- 
teries of adequate capacity. 

Where trucks are used on a single daily 
shift, the batteries can be charged while left 
in the trucks. Where this method is adopted, 
charging outlets are usually arranged along 
one or more walls of the room and space 
provided for a truck in front of each outlet. 

Where trucks are in greater use during a 
24-hour period, batteries are removed from 
the trucks for charging and exchanged for 
charged ones. 

Generally it will be found that batteries up 
to 6 kilowatt-hour size can be slid off the 
compartment of the truck onto the charging 
bench. If batteries are larger, say up to 10- 
kilowatt-hour in size, a roller-top transfer table 
is preferable. 

Exchange of batteries is most easily ac- 
complished by means of a hoist and trolley 



suspended from a tramrail or a crane. Cable 
hoists and chain hoists having a chain con- 
tainer are preferable because they provide 
a means for preventing the load or hand 
chains from contacting exposed cell terminals. 
Batteries are hoisted off the battery compart- 
ment to the charging bench, which should be 
as high as the compartment skids. 

There should be as many charging benches 
as batteries in the shop at one time. These 
benches should be of open construction to 
permit air circulation through the battery. 

Sometimes fork trucks are economically used 
for exchanging batteries from truck to bench. 
In this case it is necessary only to cut away 
enough of the drawhead on the truck to per- 
mit insertion of the forks of another truck 
under the battery. The charging benches are 
also fixed to allow the forks of a truck to be 
inserted and withdrawn from beneath the 
battery. 
Keep batteries clean and dry externally. 

Charging Batteries 

The battery shop should be located in a 
cool, well-ventilated room, with ample work- 
ing space and suitable equipment for ex- 
changing, charging, watering, and cleaning. 
Mounting control panels high on the walls 
keep them well out of the way. 

Where d-c power of suitable vottage is 



195 



PLANT MAINTENANCE MANUAL 




available, it may be used for charging bat- 
teries by employing proper control equip- 
ment. However, if the d-c voltage is not 
suitable, or if the supply is a-c, motor-gen- 
erator sets or rectifiers are applicable. 

Batteries should be charged in accordance 
with manufacturer's instructions if employing 
approved devices for terminating the charge. 
The Electric Industrial Truck Association has 
standard specifications of automatic battery 
charging motor generators, rectifiers and pan- 
els. These have been approved by the 
manufacturers. The Association can also offer 
valuable suggestions on other factors of elec- 
tric trucks. 

During the charging, the cell temperature 
should be kept below 110 deg. F. 

Never put acid into an alkaline battery nor 
vice versa and be sure not to use for servic- 



ing either, the same utensils that have been 
used for the other. 

Watering 

While there is practically no evaporation 
of water from the cells, there is some loss by 
"gassing." Whenever necessary, therefore, 
add water to bring the electrolyte up to the 
recommended level in the battery. An auto- 
matic cell filler makes the operation easy 
since it shows a light when the right level 
is reached. Be sure to use only the kind of 
water recommended by the maker of the 
battery. 

The water should be added BEFORE 
CHARGING in order to make sure that the 
water and the electrolyte are thoroughly 
mixed when gassing occurs near the end of 
the charge. This procedure is particularly 
important in cold weather. 



196 



INDUSTRIAL POWER TRUCKS 



Safety Precautions 

Wear rubber gloves and goggles when 
handling solutions. This precaution is also ad- 
visable when cleaning batteries. 

The electrolyte is injurious to the skin and 
clothing and must be handled carefully. If 
spilled on the body or clothing, it should be 
washed away immediately with plenty of 
water. 



H^ 




197 




CHAPTER 19 



ROOFS AND FLOORS 



A good roof protects the interior of a 
building and its contents— people, equipment, 
and materials— from rain or snow and heat 
or cold. 

Roofs are generally classified according to 
whether they are flat or sloping. Flat roofs, 
however, may have a slight incline or grade 
to them. The main requirement-distinction be- 
tween the two types is that steep sloping 
roofs do not ordinarily hold rain, snow, or 
ice for long periods. 

Industrial roofing materials may be prepa- 
rations of such waterproofing products as 
asphalt or pitch built-up with layers of roofing 
felts. The felts are impregnated with the water- 
proofing compound. This built-up construction 
has widespread industrial application. Where 
adaptable, so-called roll roofing, which is of 
a bituminous composition either smooth or 
mineral surfaced, also provides suitable cover- 
ing. Roofs may also be made of metal, tile, 
slate or asbestos shingles or sheets. 

Metallic roofing is laid in large sheets, 
usually corrugated for strength, or in shingle- 
size pieces which are soldered together or 
shaped like tile for interlocking. The metals 
commonly used are galvanized steel, tin plate, 
zinc and copper. Corrugated and flat steel 
sheets may also be painted or coated with 
pitch or asphalt preparations or other protec- 
tive compositions. 



Asbestos shingles and corrugated sheets 
are constructed of portland cement with as- 
bestos fibres as reinforcement. The corrugated 
sheets are applied in much the same manner 
as other corrugated materials. The shingles 
come in a variety of shapes, colors, and 
surfaces. 

Geographical location and atmospheric 
conditions are factors to consider in deter- 
mining the roofing best suited for an instal- 
lation. 

Built-Up Roofs 

Built-up roofs are widely used on industrial 
buildings. They consist of the waterproofing 
material and several layers of roofing felt, 
over which a seal coat is applied, or the 
weather side of which is mineral surfaced or 
augmented by a topping of gravel, slag, or 
crushed slate. 

Asphalt built-up roofs may be unsurfaced 
with the surface coating of bitumen being 
exposed directly to the weather, or they may 
be surfaced with slag, gravel or mineral gran- 
ules. Pitch built-up roofs are surfaced with 
slag or gravel. The felts may be of the fol- 
lowing types: asphalt saturated, tar saturated 
or asphalt saturated asbestos. 

Some of these roofing materials are applied 
hot, while others may be used in the cold 
state. 



198 



ROOFS AND FLOORS 




Specifications have been set up for the 
various types of built-up roofs which are 
bonded for periods of 10, 15, or 20 years 
depending upon their make-up, generally 
speaking on the basis of the number of plies. 
These roofs are installed according to those 
specifications by contractors or roofers ap- 
proved by the manufacturer of the roofing 
materials. 



The decks upon which these kinds of roofs 
are built up are of such constructions as 
wood, steel, gypsum, and concrete, with or 
without insulation. 

Where roof areas are to be subject to much 
foot traffic, promenade tile supplies a good 
wearing surface. If non-tiled surfaces must be 
used as traffic lanes, protect the roofing by 
duck-boards or heavier wooden walk-ways. 




199 



PLANT MAINTENANCE MANUAL 



ROOF MAINTENANCE 



Proper maintenance is necessary regardless 
of the type of roof because even the best of 
materials will eventually deteriorate when ex- 
posed day after day and night after night 
to the sun, rain, snow, sleet, wind, and other 
weathering influences. 

In taking care of roofs, preventive mainte- 
nance with its correction of minor trouble- 
causing conditions before they become major 
ones is the guiding principle. 

At the start it is well to call attention to 
the fact that good roofing is sometimes 
blamed for building ills, especially leaks, for 
which the roofing itself is guiltless. When a 
leak occurs, its source should be carefully 
sought out. 



Periodic inspections— at least twice a year, 
or more often— should be sufficient to catch 
small damages in time and keep the roof free 
of dirt and debris. A summary of what to 
inspect is given later. 

Where possible and appropriate, keep 
roofs clean by sweeping their surfaces free 
of all dirt and loose foreign material. Wash 
down with water when advisable or nec- 
essary. 

Defects in roofs include cracks, blisters, 
buckles, fishmouths, surface weathering, poor 
adhesion and rotted roof decks. Fishmouths 
are bulges in the felt at laps. Alligatoring is 
badly checked weathering of the top surface. 
Strong winds may damage roof coverings. 




r r 'r. 






Repairing Damage 



Since the top coat of a built-up roof is 
exposed to the weather, it is often the first part 
to fail. Breaks or damage to the seal coat 
permits weathering elements and forces to 
penetrate into the underlying materials. 

Maintenance repair work begins, therefore, 
at the first sign of failure in the top coating. 

If the surface shows indications of drying 



out, retreating the old roofing with a good 
coating material will help to put new life into 
it. On certain type roofs, the periodic applica- 
tion of such a coating can help to preserve 
the surface and the felt base also. If the sur- 
face is of the gravel or slag kind, bare spots 
should be repaired and more slag or gravel 
added. In patching slag, gravel or mineral 



200 



ROOFS AND FLOORS 




201 



PLANT MAINTENANCE MANUAL 



surfaced roofs, scrape off the old surfacing 
before applying the re-roofing. 

Where there are any breaks, cracks, or 
worn spots, they should be re-covered with a 
reinforcing fabric and roofing felt and appli- 
cations of weatherproofing and coating com- 
pounds and surfacing materials. Blisters may 
be slit and patched. 

If exposure of the felt has occurred at any 
place, it is advisable to recondition the old 
roof by re-saturating it with a saturating com- 
pound after patching defective spots with 
roofing fabric and felts,- followed by an appli- 
cation of a weather coating. 

In cases where the old felts have been badly 
weakened or decayed, the condition requires 
re-roofing by a new reinforcement covering 
or by replacement with new felts and water- 
proofing. 

When making repairs the old roofing should 
be swept and cleaned of dirt, grease, soot, 
etc., and a bonding preparation applied. 

It is always good practice to seek the ad- 
vice of the manufacturer of roofing materials 
for experienced recommendations. 

WHAT TO INSPECT AND WHY 

Regular and diligent inspections of all roofs 
will help to lower maintenance costs because 
they are an important feature of the "stitch 
in time" principle. Intelligent examinations 
will also disclose whether a leak, for instance, 
may not have been caused by a fault other 
than that of the roof itself. Expert roofing 
technicians are available from the manufac- 
turers for making skilled inspections and rec- 
ommendations. 

Make periodic inspections of all roofs a 
scheduled part of the plant maintenance 
program. 

Inspections should take in the following 
critical areas: main coverings, roof decks, 
drains, flashings, gutters, ladder supports, 
leaders, monitors, penthouses, scuppers, sky- 
lights, vents and ventilators. 

Main Roof Areas 

Inspect the roof generally for wear. 

Examine carefully the surfaces of the roof 
for defective seams, breaks, cracks, blisters, 
etc. Look, too, for exposed nails and for 
loose, broken or rotted boards in the roofing 
deck. 

Inspect the felts for dryness or lack of sat- 
uration and of pliability, and for weakness. 



If the felt is dry, re-saturate to restore its 
strength and pliability. 

Cracks and breaks call for reinforcement. 

Repair procedures for treating these vari- 
ous conditions have already been given. 

Flashings 

Faulty flashings cause a high percentage of 
roof troubles and leaks. 

Check flashings generally for any cracks, 
open seams at joints along parapet walls 
and curbs— in fact, anywhere that walls and 
other vertical structures or appurtenances 
meet the roof. 

Parapets and Copings 

Damaged parapet walls are frequent causes 
of leaks. Wind-driven rain and snow force 
moisture into cracks and any porous masonry. 

Spoiled walls invite weathering damage of 
all kinds with resulting troubles from seepage. 
Cracking of the coping or cap stones like- 
wise provides entrance for moisture. 

Roofing is often blamed for leaks, the real 
causes for which are weakened or damaged 
wall conditions. 

Drains 

Roof drainage systems also need periodic 
attention. Drain pipes should be properly in- 
stalled and of adequate size to handle nor- 
mal flow-off and function effectively under all 
conditions. Outlets should be guarded against 
clogging by leaves, twigs, and other storm- 
borne debris. 

Skylights, Monitors, and Penthouses 

Breaks in skylights, monitors, and penthouses 
will naturally cause leaks. So inspect them 
for cracks and breaks in the glass, faulty joints 
and seals, rusted sash, poor caulking, and 
defective flashing installations. 

Flag poles, pipe vents, ventilators, ladder 
fastenings, and tanks supports should also be 
examined closely, especially at the areas 
where they join the roof surfaces. Here again 
bad flashing should be remedied. 

Litter on Roofs 

Remove all litter from roofs. Roofs should 
never be considered as storage spots or 
places to put ladders and scaffolds out of 
sight and mind, or to hide junk of any kind. 
Not only are such objects obstructions, but 
they also readily scratch and tear the roofing 
materials. 



FIX DAMAGE WHEN IT IS LITTLE — 
AND IT WILL NEVER GET BIG. 



202 



ROOFS AND FLOORS 



INDUSTRIAL FLOORS 



Of the interior surfaces of an industrial 
plant, none is more vital than the floor. For 
floors play an essential role in the production 
and transportation system of the establish- 
ment. 

The installation, in the first place, of the 
kind of floor that will satisfy the manufacturing 
conditions to be served, therefore, is most 
important. 

For modern production areas, popular types 
of floors are concrete and wood block, both 
of which withstand severe loading and traf- 
fic and are easy to maintain. Other common 
flooring materials are plain, painted and var- 
nished wood; brick; mastic; tile ; and asphalt 
in plastic, plank or block form. Steel floor 
plates and gratings are often used in foot- 
ways, aisles, and where unusually severe 
wearing conditions are encountered. 

Sometimes sections of manufacturing areas 
are covered with linoleum, which is also used 
to a large extent in offices and vestibules. 
Marble, terrazzo, and tile are likewise found 
in the last-named applications. 

There are also many specially prepared 
compounds for re-surfacing, patching, treat- 
ing, and topping floors of various kinds. Pre- 
servatives for wood floors, rustproofers for 
metal floors, dampproofing and waterproofing 
materials, and preparations to fill holes and 
cracks, to stop dusting, and to keep out acids, 
alkalis, salts, greases, oils, and other floor 
destroyers are also available. 

Because floors that are properly constructed 
by experienced men require little maintenance 
other than cleaning, special attention will be 



paid to what constitute sound and accepted 
practices in installing the different kinds of 
industrial flooring. 

WOOD FLOORS 

Among the woods commonly used for in- 
dustrial floors are hardwood maple, pine, 
oak and the like. Modern wood floors are 
well sealed and serve satisfactorily in many 
cases where the traffic is not too heavy and 
where wood is resistant enough to the manu- 
facturing processes being performed. 

One form of wood construction which has 
given good service in carrying heavy machin- 
ery consists of a concrete base surfaced with 
an asphalt preparation, upon which a hard- 
wood is laid diagonally. A layer of tar paper 
covers the sub-base, and over the paper is 
well-matched maple flooring. 

Wood floors can usually be repaired by 
the maintenance carpenter. 

CONCRETE FLOORS 

It is just as important that correct concreting 
practices be followed in the resurfacing of 
old floors and in the repairing of defective 
ones as it is in the original construction of 
the floor. 

For production areas where heavy service 
and traffic conditions are to be served, the 
floor finish should comply wih official heavy- 
duty wearing specifications. However, where 
the concrete floors are to be covered with 
linoleum, composition tile, wood planking, 
carpeting, and other surfacing, the dust coat 
type of finish may be used. 




Spreading Concrete with Shovel and Rake 



203 



PLANT MAINTENANCE MANUAL 




Heavy Duty Floor Finish 

The topping or wearing 'course is usually 
one inch thick. Portland cement must conform 
to ASTM or Federal specifications. Both the 
fine aggregate and the coarse aggregate 
must pass the proper sieve grading require- 
ments. The nominal mixture, by volume, is as 
follows: 1 part of portland cement, 1 part of 
fine aggregate, and 2 parts of coarse aggre- 
gate which should pass a V2" sieve. Use no 
more than 5 gal. of water per sack of cement, 
including the water in the aggregate. 

Concrete may be spread with shovels and 
rakes to a fairly uniform level a little above 
the finished grade, and then tamped or rolled, 
or both. Next it should be screeded or struck 
off to grade,- then compacted with a wood 
float or by machine. Troweling further com- 
pacts the topping and produces a smooth sur- 
face. Curing, and protecting in cold weather, 
complete the work except where grinding is 
called for. 



Special Finishes 

Where unusual non-slip qualities are de- 
sired in the finish, the concrete is roughed up 
or non-slip aggregates are used. The latter 
are mixed with the concrete or sprinkled 
on the surface just prior to finishing. 

Sometimes concrete floors may be improved 
by additives that help to harden and bind 
the surface. These materials include the fol- 
lowing: magnesium and zinc fluosilicates, so- 
dium silicate, aluminum and zinc sulfates, 
Chjnawood, linseed oil and some gums, resins, 
paraffins. 

Metallic aggregates are sometimes used in 
concrete surfaces, and concrete floors may 
be armored with a network of steel grid-work, 
if desired. 

Cracks 

Cracks in concrete floors are of two classes: 
those confined to the wearing course and 
those originating in the base and extending 
through the finish. 




204 



ROOFS AND FLOORS 



If not too deep, hair cracks in the wearing 
course (called crazing) may be removed by 
grinding. Where cracks in the topping are 
deep, the affected areas should be removed 
and replaced with new material. 

Structural cracks should be filled with a 
mastic material, or in some cases with a var- 
nish and resin. Concrete may be added to 
make a thicker solution for wider cracks. 

In patching concrete floors, the old wear- 
ing surface should be chipped off to a depth 
of at least one inch, and the roughened 
surface should be saturated, and the area 
surrounding the patch wetted with water. 
After several hours of saturation, the new 
concrete is placed. 

Maintenance 

Properly constructed concrete floors require 
little maintenance other than cleaning. Peri- 
odic cleaning is essential, particularly to pre- 
vent the grinding of dirt and grit into the 
finish. 

In plants where oils, fats, brine, milk, fruit 
juices and other like products are handled— 
and spilled— the floors should be scrubbed 
frequently and thoroughly. In some cases it 
may be necessary to do so once a day". 

Dirt, oils, greases and other foreign matter 
should not be allowed to crust on the floors 
because they form uneven surfaces which add 
to the tractive efforts of plant trucks. Scraping 
and scrubbing will remove crusts of these 
sorts. 

Specific cleaning practices are discussed 
further in the section on cleaning. 



WOOD BLOCK FLOORS 

Creosoted wood blocks also provide a 
heavy-duty flooring to withstand severe truck- 
ing loads. Proper installation of the blocks is 
essential, of course, to a well-constructed, 
smooth surface. 

Standard specifications for usual industrial 
floors may include the following details-. 

Block sizes may be 2 1 /? to 4 inches wide, 
5 ] /2 to 8 inches long, and 2, 2 ] /2 or 3 inches 
deep. Variations of 1/16 inch in depth and Vs 
inch in width are permitted. 

The preservative and method of treating 
blocks should be in accordance with American 
Wood-Preservers' Association standards. 

Foundations should consist of smooth and 
level concrete sub-bases which will provide 
an even bearing for the blocks. The depth 
and strength of the concrete should be suffi- 
cient to carry the load to which it will be 
subjected. The surface of the concrete should 
have a handfloat finish and be at a level 
below the finished grade equal to the depth 
of the blocks to be used. 

The concrete base must be thoroughly 
clean and dry before the thin, uniform paint- 
coat of bitumen is applied by spraying or 
squeegeeing. The melting temperature point 
of the bitumen should be between 130 and 
150 deg. F. 

Laying the Blocks 

The wood blocks are then laid on the paint 
coat in straight, parallel lines which run at 
right angles to the direction of traffic flow. 
The blocks are driven together tightly at the 




tizfffifsi 



205 



PLANT MAINTENANCE MANUAL 



sides and the ends. Joint breaks should not 
be of less than one inch and only whole 
blocks should be used, except at the start or 
finish joints. 

For binding the joints, two coats of bitu- 
men binder are applied after the floor has 
been cut in. Application should be by squee- 
gee machine, and care must be shown in 
working the binder into the joints uniformly 
so as to leave as little binder material on the 
surface as possible. 

Maintenance 

The amount of maintenance necessary to 
keep wood block floors in satisfactory shape 
depends a great deal upon the observance 
of the above suggestions by experienced 
workers in laying the original floors. In other 
words, the better the job in the first place, 
the less is the maintenance necessary. 

In replacing sections of damaged blocks, 
be sure that the new blocks are laid to a 
grade level with the rest of the surrounding 
floor in order not to have humps in the sur- 
face. The recommendations given above for 
the condition of the sub-base and the laying 
of the blocks would apply as well to the mak- 
ing of repairs. 

Cleaning procedures are given later in 
the chapter. 

MASTIC FLOORS 

Mastic floors, which are composed of as- 
phalt or asphalt emulsions and aggregates of 
various kinds, also have considerable indus- 
trial uses. 

There are generally two kinds of mastic: 
hot and cold. The former is a mixture of hot 



asphalt and aggregate similar to what is used 
for asphalt street pavements. Cold mastic is 
an asphalt emulsion mixed with cement and 
aggregate and water. 

Heavy duty industrial mastic floors installed 
under manufacturer's specifications provide a 
flooring that is resilient and shock-absorbing 
and which will withstand heavy trucking. It 
can be used for patching, for laying over 
worn surfaces and for re-surfacing large 
areas on old surfaces and new construction 
as long as the base is reasonably strong. 

It can be applied by hand or machine to 
old wood, concrete, brick, or steel floors with- 
out extensive preparation of the old base 
other than that of cleaning it of all grease, 
dirt or foreign matter with water, lye, etc., 
and then rinsing it. Mastic can also be used 
as an underlayment for linoleum, asphalt tile 
and other resilient floors, and as a filler for 
floors armored with steel mesh or grating. 

Ruts, holes and depressions that are not 
deep enough for filling with concrete, should 
be brought to level with the mastic mix. 

In order that the primer and the surfacing 
layers may be laid in as uniform a thickness 
as possible, the hole-filling materials should 
be allowed to set first. 

Patching with Mastic 

In using cold mastic for patching, a heavy 
duty mixture is advisable. Commonly the ce- 
ment and aggregate are mixed with water 
to a workable consistency,- then the emulsion 
is added. 

The hole or rut should be cleaned of all 
loose particles, dirt, or grease; and its edges 
trimmed to a shoulder. After scrubbing with 




206 



ROOFS AND FLOORS 



a broom wet with water, a priming coat is 
applied to the hole and for several inches 
around its edge. 

When the priming coat has dried, the mas- 
tic is troweled into the hole and feathered 
off on the primed surface around the hole. 
To allow for shrinkage, the mastic should 
be left 1/16 inch higher than the surrounding 
surface. 

ASPHALT TILE FLOORS 

Asphalt flooring materials also come in 
plank, slab or tile forms which are laid as in- 
dividual blocks. This flooring is commonly 
an asphaltic mixture containing tough fibres 
and mineral filler formed under pressure. 

It possesses good resistance to wear and 
moisture and is resilient. It is readily laid on 
any smooth, firm surface. 

Another resilient flooring material— suitable 
for light manufacturing areas— is of mastic 
composition bonded to an asphalt saturated 
felt backing. This material is installed in roll 
form. 

LINOLEUM FLOORS 

Linoleum covering may be laid on almost 
any kind of sub-floor that is structurally solid 
and sound. It should not be installed, how- 
ever, in direct contact with the ground. 

Representative specifications call for the 
proper preparation of sub-floors— wood, con- 
crete, ceramic tile, terrazzo, marble, metal- 
including all repairs necessary to bring them 
to a smooth, even surface. Installation is 
usually performed by a qualified contractor 
working according to these standard specifi- 
cations. 

Under no conditions should linoleum be 
laid on damp concrete. Concrete, therefore, 
should be allowed to dry thoroughly and, if 
necessary, tests should be made to determine 
any dampness. 

Seams and joints with vertical surfaces 
should be made with great care and accuracy 
to insure tightness. When the linoleum is pat- 
terned, the edges should be carefully matched 
at all seams. 

Laying 

Linoleum should be laid so that the under 
surface is completely and securely bonded 
and the upper surfaces smooth and clean. A 
roller should be used to paste down the lino- 
leum, and the lining where it is included, and 
to eliminate air bubbles for strong and com- 
plete adhesion. The seams and edges should 
also be rolled. 

Adhesives may be linoleum paste or water- 
proof cement, according to which is required. 



Both paste and cement are usually spread on 
with a notched Trowel. Excess paste should 
be wiped off the surface with a water-damp 
cloth immediately. Cement should be removed 
from the surface of the linoleum with fine 
steel wool. 

Maintenance 

Correct care of linoleum will keep it in 
good condition and make it last longer. Main- 
taining linoleum floors by frequent and proper 
waxing is an important factor in insuring long 
wear and good appearance. Frequent wax- 
ing also makes washing less necessary. Be- 
sides adding to the wearing qualities, the 
wax film helps to prevent dirt from being 
ground in and provides lubrication to reduce 
surface wearing. 

A good type of wax can be applied with 
a cotton cloth or a special applicator. Apply 
thin coats, using as littie wax as possible. 
Buffing by hand or machine produces a high 
glossy finish. A self-polishing wax provides 
the best results. 

Waxed floors should be brushed daily with 
a soft hair brush to remove the dirt or dust. 

CLEANING FLOORS 

If for no other reason than the safety angle, 
it is always necessary to keep industrial floors 
clean. For foreign matter such as grease, oil, 
wax, metal chips and turnings, wood shavings, 
and the like add to slipping and other haz- 
ards. 

On the other hand, clean floors add to 
floor life and appearance and help worker 
morale in eliminating dirty working condi- 
tions. Yet this phase of plant maintenance is 
often neglected. 

A definite floor cleaning program and rou- 
tine should be established. In his connection 
sweepers and janitors can be assigned spe- 
cific areas which they are to keep clean. 

The selection of the right kind of cleaner 
depends upon the kind of floor surface and, to 
a lesser degree, upon the kind of dirt to be 
removed. 

Most industrial dirt is a mixture of oil, 
grease and solid materials of many varie- 
ties. Where processing operations deposit 
considerable foreign matter, periodic sweep- 
ing schedules should be set up in order to 
prevent large accumulations of dirt. These 
sweeping routines do not eliminate the regular 
cleaning of floors as sweeping alone does 
not always remove the solid matter that is 
ground into floor surfaces. 

Since these deposits tend to embed them- 
selves in, or bond themselves to, the surface, 



207 



PLANT MAINTENANCE MANUAL 




it is necessary to loosen and remove the for- 
eign matter first by scraping, either manually 
or by machine. 

Various kinds of cleaning machines are on 
the market. They include the following: sweep- 
ers, polishers, burnishers, sanders, scrubbers, 
brushes, dirt cutters and vacuum cleaners. 
There are also magnetic type sweepers which 
pick up filings, chips, and other ferrous ma- 
terials. 

Whether the cleaning is done by hand or 
machine, however, needless and excessive 
brushing and scrubbing should be avoided. 

Cleaning Materials 

Many excellent cleaning compounds are 
available, and their manufacturers will make 
reliable and appropriate recommendations 
for those most suitable for any given condi- 
tions. In general, compounds for machine 
washing may be less concentrated solutions 
than those for manual operations. Some spe- 
cific cleaning suggestions follow-. 

CONCRETE — Warm, soapy water can be 
used for cleaning concrete floors. It is worked 
either with a stiff brush or with an electric 
scrubbing machine. Floors should be mopped 
clean. 

Moderate alkaline cleaners are also usu- 
ally satisfactory, since they wet and emulsify 
the oil and grease. Strong alkalis, acids, and 
volatile solvents like gasoline and benzine 
should not be used— the last two in particular 
because of their fire and explosive hazards. 



The cleaning solution is allowed to soak for 
a few minutes before it is mopped or brushed 
up, after which the surface is rinsed, prefer- 
ably with a hose. 

An emulsifiable solvent cleaner may also 
be used on concrete where oily and greasy 
deposits are ordinary. 

On terrazzo and other decorative concrete 
finishes, warm soapy water should be em- 
ployed, and the soap thoroughly rinsed off. 
A solvent type of cleaner may also be used. 

WOOD— Care must be taken in selecting 
the right sort of cleaner for ordinary unpainted 
and unvarnished wood floors in order not to 
damage them. 

Since wood floors are often slippery when 
wet with water, soaps would tend to increase 
that hazard. Therefore, compounds contain- 
ing soap should be avoided in certain cases. 
Although heavy alkaline action can damage 
wood structures, especially where there are 
scralches or gougings, it may be necessary 
to use an alkaline cleaning solution to remove 
the oily and greasy dirt that adheres to the 
floor. 

Thorough rinsing of wood floors is essen- 
tial in that it permits the wood to dry faster. 

Where floors are painted or varnished, 
however, a solvent-soap type of cleaner 
offers good results because it does not attack 
the finish as an alkali would. 

WOOD BLOCK-Floors made up of creo- 
soted wood blocks do not have the same 
characteristics that ordinary wood floors have. 




208 



ROOFS AND FLOORS 




The impregnated blocks resist water, grease, 
oil, and acids. However, grease and oil de- 
posits, and water to a lesser degree, can 
make the floor slippery. 

An alkaline compound containing a solvent 
and a wetting agent which penetrates the 
dirt deposits, emulsifies grease and oil, and 
holds solid dirt in suspension is suggested for 
cleaning exposed surfaces of the wood blocks. 

Procedures and cleaners recommended for 
concrete floors are also suitable for wood 
block floors. 

UNOLEUM-The less the washing, the better 
it is for the linoleum. But when washing is 
desirable, use only mild soaps— those mild 
enough for application to the skin or fine gar- 
ments. Suitable compounds that remove dirt 
without harming the material may also be 
used. 

Whatever cleaning product is employed, 



use lukewarm water solutions. Apply with mop, 
cloth, scrubbing brush, or machine,- then be 
sure to rinse with clear, cold water. 

Never use strong soaps or gritty scouring 
materials on linoleum. 

MASTIC— In cleaning floors of this type a 
neutral soap compound possessing some solv- 
ent action usually gives good results. Do not 
use damaging alkalis. 

Absorbent Compounds 

Some floors may be treated with oil-absorb- 
ent material preparations which have a "blot- 
ter" property to oil and grease. Spread 
around machines and other oil-soaked areas, 
the compound absorbs the oil and grease, 
and the accumulation of dirt can be easily 
swept up. Periodic treatment of this sort 
can restore the floor to its original condition. 




209 




CHAPTER 20 

— PUMPS — 



Pumps — the mechanical movers of liquids 
— are manufactured in a wide variety of de- 
signs and capacities for all manner of applica- 
tions. The movement of liquids is accomplished 
by impellers, pistons, plungers, gears, cams, 
rollers, vanes, rotors and other devices housed 
in casings or cylinders. 

In size, pumps may vary from those needing 
only a fraction of a horsepower to drive them 
to those requiring several thousand. In capac- 
ity they are made to handle fluids up to thou- 
sands of gallons per minute. Pumps are also 
designed to operate under normal or unusual 
atmospheric conditions and against pressures 
of a fraction of a pound per square inch up to 
tens of thousands of pounds. 

Materials used in the construction of pumps 
include iron, alloy steels, bronzes, rubber, 
glass and stoneware — to mention only a few. 

The three basic types of pumps most com- 
monly used in industry are centrifugal,recipro- 
cating, and rotary. 

Selecting the Right Pump 

Selection of the right kind and size of pump 
for the conditions to be served is most impor- 
tant because many of the troubles that may 
develop in pumps are caused by a lack of 
consideration of those conditions. Another es- 



sential element in any efficient pumping pro- 
ject is +o have the proper size of pipe on both 
the suction and the discharge sides of the 
pump. 

To insure, therefore, that the right kind of 
pumping installation is secured for the job to 
be done, consult with the manufacturers of 
pumps for their experienced recommendations. 

Among the factors that influence the selec- 
tion of the right equipment, and which should 
be given to pump makers for their guidance, 
are the following: 
CAPACITY, SPEED, AND SERVICE-. 

Capacity in U. S. gallons per minute (gpm). 

Speed of operation in revolutions per min- 
ute (rpm). 

Kind of service — continuous or intermittent; 
if latter, supply details. 

Number of pumps needed. 
LIQUID HANDLED: 

Name or description. 

Pumping temperature. 

Specific gravity and viscosity, if other than 
water. (If water, state whether fresh or 
salt and give other characteristics.) 

Presence of solids or abrasives. (If any, de- 
scribe them.) 

When aciduous or alkaline give pH value. 



210 



PUMPS 



DISCHARGE LINE: 

Pressure in pounds per square inch, or the 

head in feet. 
Discharge head, and any variations in head. 
Diameter of pipe. 
Total length of pipe line. 
Number of elbows, 45 and 90 degree. 
Number of valves, tees, etc. 

SUCTION LINE: 

Suction lift, and any variations in lift. 

Diameter of pipe. 

Total length of pipe. 

Number of elbows, 45 and 90 degree. 

Number of valves, tees, etc. 

The matter of the kind of drive for the pump 
is another important consideration. The pump 
may be driven by an electric motor; a gas- 
oline, oil, or steam engine; or a steam turbine. 
Power may be transmitted from the prime 
mover to the pump by belt, chain, or gears, or 
by direct connection. 

Pump Language 

CAPACITY — amount of liquid in gallons per 
minute (gpm). Divide the number of gallons to 
be pumped by the number of minutes in which 
the job is to be done. 

STATIC SUCTION LIFT - vertical height (in 
feet) from the level of the liquid supply to the 
centerline of the pump. 

TOTAL SUCTION LIFT -static suction lift 
plus the friction losses in the entire length of 
the suction line. 

SUCTION HEAD -difference, or distance 
between the level of the source of. liquid sup- 
ply and the centerkne of the pump, when the 
latter is below the source of supply. 

FRICTION LOSS IN PIPE-resistance to flow 
by the inside wall of pipe and fittings. Varies 
with the size of pipe, the number and kinds of 
fittings, and the viscosity of the liquid. Values 
are obtained from tables. 

STATIC DISCHARGE HEAD- vertical dis- 
tance from the centerline of the pump to the 
point of discharge of the liquid. 

TOTAL DISCHARGE HEAD-static discharge 
head plus friction loss in entire discharge pipe 
line plus pressure required at point of dis- 
charge. 

TOTAL NET HEAD -total suction lift plus 
total discharge head. 




PROPER SELECTION AND CARE OF YOUR PUMPS WILL LENGTHEN 
THEIR LIFE AND PREVENT TROUBLESOME AND COSTLY SHUT-DOWNS, 



211 



PLANT MAINTENANCE MANUAL 



HIGH LIGHTS OF LOW-COST PUMPING 

a. Obtain the right pump for the job to be done. 

b. Install pump and drive properly and maintain 
them in correct alignment. 

c. See that the piping is installed for the most 
effective operation. For instance, horizontal pip- 
ing on suction line should slope upward, not 
downward, toward the pump. 

d. Check piping supports to see that there is no 
strain on the pump casing. 

e. Be sure the intake end of suction pipe is screened. 

f. Pump only those liquids for which the pump is 
designed. 

g. Operate pump near its rated head only. 

h. Keep pump installation clean and maintain it in 

good running order. 
i. Lubricate the bearings sufficiently with the right 

lubricant, 
j. Do not let pump run dry either from lack of prime 

or from loss of suction. 
k. Inspect the pump regularly, examining all parts 

carefully for wear and damage. 



Installation 

Pumps which are correctly selected for the 
required service conditions and properly in- 
stalled require little maintenance. 

For the best operation, a pump should be 
situated as close to the source of the liquid 
supply as possible. Furthermore, it should be 
located in a clean, light, dry place with good 
air circulation and easily accessible for in- 
spection. Protect pump from dirt and dust; 

Pumps should have rigid and substantial 
foundations to absorb vibration and hold all 
working parts, connections, and piping in cor- 
rect alignment. 

Pipes should line up naturally with the pump 
and be supported independently of the pump 
in order not to strain the casing. 

Priming 

There are several means of priming a cen- 



trifugal pump operating under a suction lift. 
One is to install a foot valve at the inlet end 
of the suction pipe. The liquid for priming may 
come direct from some outside source, through 
a separate priming pump, or by way of a by- 
pass around the discharge check valve. Since 
any failure of a foot valve will permit a pump 
to lose its prime, the valve should be inspected 
and cleaned frequently. 

Priming by removing air from the pump cas- 
ing and the suction pipe may be accomplished 
by the use of a vacuum pump or an ejector, or 
exhauster, operated by air, steam or water. 

Several automatic priming arrangements are 
also available. One device consists of a two- 
compartment tank which is so designed that 
the lower, or primer, compartment, supplies 
sufficient liquid for priming purposes. Other 
automatic systems make use of a vacuum pump 
or a special priming pump. 




212 



PUMPS 




213 



PLANT MAINTENANCE MANUAL 



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PUMPS 



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215 



PLANT MAINTENANCE MANUAL 



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216 



PUMPS 



CENTRIFUGAL PUMPS 



As the name implies, centrifugal pumps move 
liquids by means of centrifugal force. Basic- 
ally, they are of two forms— volute and dif- 
fuser. 

In a conventional volute pump the liquid is 
guided from the suction line to the center of 
a rotating impeller. The vanes of the impeller 
force the liquid radially into the outer part of 
the pump casing which is called the "volute." 
The volute collects the impelled liquid, con- 
verting its velocity head into pressure head, 
and directs the flow to the discharge line. 

The turbine or diffuser pump does not have 
a volute channel. The liquid passes through 
diffuser vanes and is delivered to the channel 
of the pump casing that encloses the vanes. 

A third form is a combination of the two— 
a diffuser pump with a volute— and is called 
a volute-and-turbine pump. 

Another pump for this general type, al- 
though not strictly centrifugal with the liquid 
flowing radially, is the propeller pump. In it the 
liquid is pushed or impelled axially by the 
propeller. 

Still another variation is the mixed-flow type 
in which the liquid passes through the pump 
in an inclined direction. 

Fundamentals 

Single stage centrifugal pumps have one 
impeller while in multistage pumps the liquid 
passes successively through a series of im- 
pellers. Centrifugal pumps are either vertical 
or horizontal according to the position of the 
pump shaft, and they are single or double 
suction depending upon whether the impeller 
has one suction inlet or has two inlets. 

Impellers are open or closed, based on the 
respective absence or presence of sidewalls 
from the eye to the outer circumference of 
the tips of the vanes. Centrifugal pumps are 
built with many kinds of impellers. In one com- 
mon type the impeller is attached to the shaft, 
with sleeves extending outside the shaft to 
protect the latter from the liquid. The shaft is 
connected to the power driver directly, or by 
belts, chains or gears. Stuffing boxes with 
packing prevent leakage along the shaft. 

Other essential parts are the wearing sur- 
faces—where the rotating and the stationary 
parts are close together to prevent the flow 
of fluid from the high- to the low-pressure 
side. 

A modern trend in centrifugals, incidentally, 
is to combine the pump and the drive motor 
in a compact, single-unit package. 




VOLUTE 



Volute Pump 



CASING 

DIFFUSION 
VANES 
IMPELLER 




Turbine or Diffuser Pump 



VOLUTE 

DIFFUSER 
FIXED 




IMPELLER 
VANES 

Volute and Turbine Pump 



217 



PLANT MAINTENANCE MANUAL 



When operating on a suction lift, centrifu- 
gal pumps will not function unless the casing 
and suction line are full of liquid. Some means, 
therefore, is usually provided for priming them. 
If, however, the level of the liquid supply is 
such that it flows to the pump, the pump can 
be made to prime itself. 

Care and Maintenance 

Preventive maintenance can keep a pump 
up to its original efficiency and in good run- 
ning order. Essential to such maintenance are 
periodic inspections; and one of the most im- 
portant tests is that of observing any reduc- 
tion of the total head developed and the 
actual capacity delivered from the rated head 
and capacity of the pump. A reduction in 
either is a symptom of wear that should be 
remedied. 

Since operating conditions vary so widely, 
it is difficult to set an arbitrary inspection and 
maintenance schedule. The following pro- 
cedures, therefore, should be adjusted to 
meet the individual needs of each case as 
operating experience dictates. In any event, 
follow the manufacturer's recommendations as 
to materials and methods for the care of his 
products. 




Maintenance Schedule 

EVERY MONTH 
Bearings: 
Check temperatures. Causes of "hot" 
bearings are: sleeves, not enough lu- 
brication,- anti-friction, too much lubri- 
cant. 
Change oil as necessary. 

EVERY THREE TO FOUR MONTHS 
Bearings: 

Inspect and clean. Drain lubricant from 
bearings and housings and clean with 
suitable cleaner. 

Sleeve bearings: Check clearance against 
manufacturer's recommendations; in- 
spect oil rings for free turning. Repair 
or replace, if necessary. Refill with 
proper lubricant. 

Anti-friction bearings: Flush, clean, and 
examine for wear and pitting. (The 
chapter on the maintenance of anti- 
friction bearings gives information on 
their care. 

EVERY SIX MONTHS 
Stuffing box: 

Watch for excessive leakage of sealing 

liquid. 
Inspect packing for wear and damage. 

Replace if defective. 
Check position of lantern rings. 
Shaft sleeves: 

Examine for trueness, scoring and wear. 
Pump and Driver-. 

Check alignment. Realign if necessary. 
Examine piping supports and look for 
strains on pump caused by poorly sup- 
ported pipe. 

EVERY YEAR 
Impeller: 

Inspect for wear from abrasion, corro- 
sion, and cavitation. (Cavitation is the 
pitting from the hammering effects of 
recondensing vapor bubbles.) 

Casing: 

Check similarly, if impeller is badly worn. 
Look for scales and foreign matter. 
Wearing Surfaces: 

Check clearances between stationary and 

rotary parts. 
Foot valves, check valves, and strainers: 
Inspect for condition and obstructions. 
Pipe conditions: 
Test by measuring total dynamic suction 
and discharge lifts. 



218 



PUMPS 




RECIPROCATING PUMPS 

Reciprocating pumps may be horizontal or 
vertical, piston or plunger, single or double 
acting, and steam cylinder or power driven. 

Direct-acting steam cylinder pumps are 
either simplex or duplex. Simplex pumps have 
one steam and one liquid cylinder while du- 
plex pumps have two duplicate cylinders on 
both the steam and the liquid sides. Steam 
pumps, having a crank and flywheel arrange- 
ment, may be simplex, duplex or triplex double 
acting, or triplex single acting. 

Motor-driven pumps are simplex, duplex, 
triplex or quintuplex in cylinder arrangement. 
The pistons or plungers may be connected to 
a crankshaft geared to a countershaft. Power 
transmission from the driving motor may be 
by flat or V belts, chains, or gears. 

Deep well pumps are designed for use 
where the water supply is not within suction 
distance and does not flow. 



There are, of course, many designs of valves 
and valve gear arrangements. 

Since their discharge pulsates, reciprocating 
pumps are often supplied with air chambers 
to cushion and smooth out the flow. The air 
in the chamber is compressed during the dis- 
charge of the liquid, and the expansion of 
the air tends to keep the liquid flowing uni- 
formly until the reverse or next stroke takes 
effect. 

Reciprocating pumps, being of the positive 
displacement type, ordinarily prime themselves. 

Care and Maintenance 

Most of the general suggestions regarding 
good installation, efficient operation, and pro- 
per maintenance of centrifugal pumps apply 
also to the reciprocating kind. But since re- 
ciprocating pumps do differ from other pumps 
in construction, there are naturally specific 
recommendations that apply only to them. 



219 



PLANT MAINTENANCE MANUAL 



A good operating practice in most cases, 
for instance, is to make the pump run with a 
full length of stroke. Also, pumps should be 
moved daily, or even more often, if there is 
a possibility of freezing. Furthermore, one of 
the most common causes of poor operation 
is too small a suction pipe. 

When necessary to make adjustments, fol- 
low manufacturers' instructions regarding pro- 
cedures and materials. 

Parts found in reciprocating pumps requir- 
ing periodic inspection and maintenance at- 
tention include the following: 

Valve and valve gears: on liquid ends and 
steam ends; boxes and seats; steam valve 
chest. 

Plungers, pistons and piston rings. 

Cylinders: liquid, steam, and valve. 

Rods, crankshafts, crossheads and gears. 

Stuffing boxes, glands and packing. 

Bearings: sleeve and anti-friction. 



Glands should be set up equally and with 
care— not too hard. 

Steam valves and valve gears should be 
removed frequently and cleaned with a suit- 
able cleaner. Valves, pistons, and piston rings 
should be checked for tightness. 

In a steam pump, the valve chest is a most 
vital part and is subject to considerable wear. 
Scoring and ridges may be removed by filing 
and the surfaces smoothed with an abra- 
sive stone. 

Slide valves, too, may be scored and 
ridged, and should be smoothed periodically. 

The right selection, use, and replacement of 
packing helps to reduce maintenance costs. 

Outside moving parts should be lubricated 
with mineral oil. No oil, however, should be 
used in steam or water cylinders or valve 
chests. Only a small amount of cylinder oil 
should be used on the steam end of rods. 



ROTARY 

Rotary pumps are of the positive displace- 
ment type. Their liquid-driving mechanisms are 
of several forms such as gears, lobes, screws, 
rollers, vanes, rotary plungers, eccentric pis- 
tons, and universal joints. These devices trap 
the liquid in the suction side of the pump 
casing and force it over to the discharge side. 
Very close clearances are maintained be- 
tween the rubbing surfaces. 

In geared pumps, the impellers may be 
spur, herringbone or helical or spiral gears. 
In the spur gear kind, for sake of illustration, 
two meshing gears rotate in opposite direc- 
tions. The liquid is carried from the suction 
side to the discharge between the gear teeth. 
The tight meshing of the two gears prevents 
any fluid from returning to the suction side. 
One gear is attached to the drive shaft while 
the other is an idler. 

Internal-gear pumps also come in various 
forms of construction. In one design, for ex- 
ample, the rotor has a gear mechanism on 
its outer circumference which meshes with 
and drives an off-centered, smaller gear which 
in turn rotates inside a crescent-shaped seat 
between the suction and the discharge pas- 
sages. 

Lobe pumps operate like the gear-type in 
that the lobes form pockets in the casing 
in which the liquid is carried around to the 
discharge. 

Screw pumps may have a single screw or 
two meshing screws that drive the liquid 
along. 



PUMPS 

Vane pumps have vanes which slide or 
swing. In the swinging vane (or bucket) type, 
for instance, the vanes, which are hinged or 
articulated, swing outward by centrifugal 
force to contact the casing bore. The vanes 
impel the liquid through the pump. 

Pump Care 

The average rotary pump is a relatively 
simple mechanism. Nevertheless, correct in- 
stallation and proper alignment of all its parts 
are necessary for satisfactory operation. In 
connecting the piping to the pump, therefore, 
care should be taken not to twist or strain 
the assembly. 

Pump condition can be determined by 
noting the pressure head and comparing it 
with the rating of the pump shown on the 
nameplate. 

The general precautions and procedures 
already given for other kinds of pumps also 
apply to rotary as well. 

Keep the bearings of the pump and its prime 
mover lubricated at all times. If the unit is 
reduction-geared, check the level of the oil 
in the gear box. If clutch gears are used, 
keep the clutches properly adjusted and lu- 
bricated. Wherever located, grease cups 
should be turned down frequently, especially 
when the pump works continuously. 

In many applications, rotary pumps lubri- 
cate themselves internally by the liquid being 
pumped. Because of this fact, it is important 
to keep the liquid as clean as possible to 
prevent foreign matter from entering the pump. 



220 



PUMPS 



Stuffing boxes should be inspected from time 
to time for excessive leakage, and be kept 
properly adjusted. The glands should not be 
too tight or too loose— tight enough to permit 
the slight leakage necessary for lubricating 
the packing, yet loose enough so as not to 
bind the shaft. 

Inspect packing for wear, dryness, or other 
deterioration. Replace at frequent intervals. 
When repacking be sure that stuffing box is 



clean. If lantern rings are used, check them 
for right positioning. 

Inspect rotating parts and housing periodi- 
cally for wear. If badly worn, replace. Main- 
tain clearances between pump rotors and cas- 
ing wearing plates and cylinder liners in ac- 
cordance with pump specifications. 

Be sure to follow the manufacturer's instruc- 
tions for the repair and replacement of pump 
parts. 




221 



PLANT MAINTENANCE MANUAL 




CHAPTER 21 

— VALVES — 



Valves are used for controlling— starting and 
stopping and regulating the volume, rate, or 
direction of— the flow of fluids in pipe lines. 

Basic types of valves are gate, globe and 
angle, and check. Angle valves are essentially 
of the globe variety. Other names applied to 
valves include the following: cross, needle, 
Y, blow-off, safety, relief, stop-and-check, 
butterfly and trap. Plug cocks are also of dis- 
tinct design. 

This chapter will treat, however, only of 
the basic types mentioned above. It should 
be clearly understood that there are several 
kinds of constructions for each of these basic 
types and the valves illustrated show only 
one of several possible constructions. The 
sketches, therefore, are used merely for the 
purpose of showing general features, and 
not to imply any special advantage of one 
kind over another. 

Materials 

The metals most commonly used for valves 
are bronze, iron and steel. Valves are also 
made of alloys of those metals with aluminum, 
chromium, manganese, molybdenum, nickel, sili- 
con and silver as well as of pure silver and 
nickel. Consult manufacturers and follow their 
recommendations. 



End Connections 

End connections of valves are of several 
kinds— screwed, flanged, union, brazed or 
welded. Usually the kind and size of pipe 
influences the sort of end used. All kinds are 
not necessarily used on all valves. 

The more common of the screwed joints 
are those with female threads. However, male 
pipe threads may be supplied on both ends 
or on one end with the other either a female 
thread or flange. 

Union ends are a form of screwed joint 
and furnish connections which are easy to 
separate without disturbing the piping. One 
or both ends may be supplied with a union. 

An advantage of flanged ends is that the 
valves are easier to remove from the line for 
inspection and reconditioning, since the un- 
bolting of the flanges is all that is necessary 
for sliding the valve out of the line. 

Connections may also be made by brazing. 
Silver brazed joints are high temperature, vi- 
bration, and corrosion resistant and strong. 

Welding ends are generally limited to steel 
valves. 

The Better the Installation, the Less the 
Maintenance. 



222 



VALVES 



Bonnet Joints 

Bonnets may be fastened to the bodies of 
valves by means of screwed, union, flanged 
or soldered joints. 

Screwed joints are commonly male dnd fe- 
male threaded with the bonnet usually carry- 
ing the male thread and the body the female. 
The bonnet, however, may be screwed over 
the body. 

In the union joint the ring nut is screwed 
down over the neck of the body. 

Bolted bonnets are usually found on large 
valves and are supplied with gaskets for 
tightness. 

Stems end Spindles 

Stems or spindles of the screw type are either 
outside or inside screw and rising or non- 
rising. Stems with inside screw have the 
threads inside the valve and thus exposed to 
the fluid. In outside screw valves the thread 
on the stem is outside the valve, the spindle 
packing coming between the thread and the 
fluid. 

In the rase of rising stems in inside screw 
valves, the threads on the spindle and those 
of the bonnet engage, thereby raising the 
spindle and the wedge, plug, or disc with it. 



The height to which the stem rises indicates 
the extent to which the valve is open. 

In inside screw valves which have non-ris- 
ing stems, the spindle threads into the wedge 
or discs of a gate valve, for instance, raising 
the latter to open the valve. All gate valves 
with non-rising stems are of the inside screw 
type. 

All outside screw valves have rising stems. 

Quick-opening valves are similar to rising 
stem-screw type, except that threads are omit- 
ted and operation is by lever or other means 
for raising the stem. The gate valve of this 
type is also made with rotating stems — a 
quarter turn or less opening them. 

Operation 

Gate, globe, and angle valves are usually 
operated by various kinds of standard hand 
wheels or levers. 

There are, however, other means for op- 
erating large valves and those difficult to 
reach or inaccessible. Large or high pressure 
valves may be regulated by electric motors. 
Gear mechanisms, sprocket rims, hydraulic 
power (air, water, oil) are also available for 
hard-to-reach locations. For valves in trenches 
or on ceilings below, floor stands are quite 
suitable. 




GATE 




CHECK 



GLOBE 





ANGLE 



BASIC TYPES OF VALVES 

i ■ 



223 



PLANT MAINTENANCE MANUAL 



Hand Wheel 



Outside Screw and 
Yoke (O.S.&Y.) 

Gland 
Packing 




Gate Valves 

Gate valves are designed to permit either 
a straight, full-and-free flow of the fluid or no 
flow at all. They offer less resistance than 
the other basic types described. They should 
be used where pressure drop through valves 
is important and where valves are normally 
to be wide open or completely closed. They 
are not intended to provide a throttling action 
or close control of the line flow. 

A gate, of wedge or disc character, is 
raised or lowered to open or close the valve 
to the flow stream. The wedges or discs are 
of several kinds, such as: solid wedge, split 
wedge, wedge disc, double disc-taper seat, 
double disc-parallel seat. 

The valve seats are either an integral part 
of the valve body or a renewable ring. In 
the latter case the ring, of different material 
from that of the body, may be screwed, 
welded, or rolled tightly into place. 

Stems or spindles may be non-rising, inside 
screw; rising or traveling, inside screw,- or 
rising, outside screw and yoke (O.S. & Y.). 
These spindle or stem characteristics, and the 
bonnet construction features, are discussed 
under those specific headings. 




224 



VALVES 



Globe and Angle Valves 

An important use of globe valves is to regu-„ 
late or throttle the volume or rate of flow 
of the fluid from trickles to full capacity. 
These valves operate efficiently with the stem 
in any position from wide open to tight closed. 
Globe valves reduce pressure considerably, 
and it is possible, of course, to use them to 
stop the flow completely as well as to per- 
mit full flow. 

Angle valves have much the same internal 
construction as globe valves except that the 
direction of flow is changed. Angle valves are 
often used in place of 90-degree fittings. 

In globe and angle valves the seating ele- 
ments may be regrindable or renewable, 



metal or composition. The seat may be an 
integral part of the diaphragm or a remov- 
able ring of a variety of materials. Discs or 
plugs are of metal or composition. Throttling 
types have plug-disc, full-plug, semi-plug, 
full-cone and semi-cone discs. Stop types are 
flat disc, bevel disc, etc. 

Globe and angle valves operate with rising 
stems of either inside or outside screw con- 
struction. These features and those of the 
bonnet design are covered in other sections 
of the chapter. 

Needle valves, a form of plug globe or 
angle valves, are used where very close 
regulation of flow is desired. In these valves 
the spindle has a needle-like point. 




GLOBE VALVE 





ANGLE VALVE 



225 



PLANT MAINTENANCE MANUAL 



Check Valves 

The purpose of check valves is to prevent 
the reversal of the direction of flow in a pipe 
line. With the exception of the screw-down 
stop-and-check valve— a check valve with a 
globe valve type spindle— check valves do 
not have any external control. The pressure 
of the flowing fluid keeps the valve open, 
while gravity plus any flow reversal closes 
it. The action of these valves is automatic. 

Two kinds of check valves are the swing 
and the lift. Both may be of the horizontal 
or angle style, with the lift type having a third 
variant, namely vertical. Check valves are 



made with one-piece or union caps or bolted 
covers. 

In swing check valves the disc is hung to 
the neck of the body. These discs may be 
of the regrinding sort or of renewable com- 
position form. 

In lift check valves the disc or ball is raised 
in guides from its seat by the pressure of the 
fluid flow. The bodies and the internal pat- 
terns of the horizontal and angle styles are 
much the same as those of the globe and 
angle valves, minus the stems. The vertical 
type is more limited since it is used on verti- 
cal piping in which the flow is upward. 




LIFT CHECK 



SWING CHECK 



There is a Right Valve for Every Service- 
Use the Right Valve in the Right Place. 



226 



VALVES 



INSTALLATION 

An essential to low maintenance and long 
life of valves is the use of the right type of 
valve for the service it is to perform. An ele- 
mentary point in this connection that should 
be observed, for. example, is that a gate 
valve should never be used to provide a 
throttling action— globe and angle valves can 
be used for that purpose. If a gate valve is 
used partially open, the gate and seat are 
subjected to an erosive wear for which they 
were not intended. 

Other factors which influence the selection 
of the proper valve are the kind of fluid 
handled, the amount of flow, the pressures 
and temperatures involved, and the frequency 
of operation of the valve. 

The sort of service required and the liquids 
to be handled largely determine the kind of 
metal and material of which the valve and its 
parts are composed. 

The recommendations of responsible valve 
manufacturers should be solicited and ob- 
served in selecting valves, giving them com- 
plete information on service conditions. 



Proper Location 

Another important insurance against valve 
trouble is the correct placement of valves in 
a pipe line. For example, with valves having 
rising stems, care should be taken to provide 
sufficient clearance for opening the valve 
completely and for removing the stem and 
the bonnet yoke. 

Valves should be located— if possible and 
especially if they are to be operated fre- 
quently—so that they can be easily and safely 
worked. Inconvenient location of valves leads 
to carelessness and haphazard handling, and 
to incomplete opening and closing or other 
degrees of regulation. If jt is necessary to 
install valves in places difficult to reach, use 
chains and sprockets, extension stems or some 
other suitable device previously mentioned. 

Do not place valves where they are ex- 
posed to damaging bumps or blows from 
plant vehicles. 

Keep valve spindles vertical wherever pos- 
sible. 

Proper line identification of valves is im- 
portant for quick and emergency operation. 




PROVIDE SUFFICIENT SUPPORTS 



Provide Sufficient Supports 

Adequate support is essential to every pipe 
line, and it is good practice to place supports 
near valves, preferably on both sides of 
them. The line should be properly supported 
before any valves are installed. In most in- 
stances 10 ft. spacing between supports is 
sufficient, unless heavy equipment is used. 

A pipe line should never be allowed to sag. 



Use Proper Wrenches 

Wrenches of the right kind and size should 
be used for installing screwed end valves 
in the line. Furthermore, apply the wrench to 
the pipe end of the valve— not on the free 
side. Another precaution is to avoid too much 
leverage in pulling up a joint. 

Do not use a pipe wrench on a hexagonal 
valve end. 



227 



PLANT MAINTENANCE MANUAL 




Wrong 



PROPER WRENCHING 



Clean Valves Before Installing 

Before installing a valve, clean the inside 
of it and of the pipe line by blowing with air 
or steam or by flushing with water. Dirt, scale, 
chips and accumulations in the pipes while 
in transit or in storage, or from processing or 
threading should be removed. Other kinds of 
foreign matter which can clog and foul pipe 
lines and valves are particles of joint com- 
pound, metal, wood, cloth, sand, gravel, glass 
and paper. 

Examine the pipe lines to see that they are 
clear before closing them. 



Threading Pipe 

Follow American standard pipe threads. 
Threads that are too long for the valve joint 
permit the pipe to press against the valve 
seat or diaphragm, thereby damaging it. 

Threading the pipe to the correct diameter 
is also necessary for a proper fit between 
pipe and valve. 

After cutting, the threads should be brushed 
or swabbed completely clean. Threading com- 
pound should be applied sparingly to the 
pipe threads only— not to the valve or fitting 
end. 




TIGHTENING FLANGED JOINTS 

228 



VALVES 



Tightening Flanged Joints 



In connecting flanged ends, tighten the 
oint by the cross-over method of pulling up 
oolts in a diametrically opposite sequence 



rather than in direct order around the flange. 
An even, gradual pull insures uniform pres- 
sures and stresses. 



TEN TOP 

"MUSTS" 

OF MAINTENANCE 



V 



Use the right valve for the service. 
Locate valves for convenient operation. 
Install valves properly. 
Inspect valves frequently. 
Service valves at first sign of a leak. 
Keep valves and pipe lines clean. 
Lubricate and pack valves adequately. 
Replace or repair worn parts. 
Apply the proper wrench correctly. 
Instruct workers In valve maintenance. 



MAINTENANCE 



Causes of valve failure are: abrasive wear, 
abused spindles, accumulations of deposits, 
careless operation, damaged seating elements, 
destructive dust and dirt, excessive corrosion, 
foreign particles in the line, ignorance, im- 
proper type choice, incorrect gaskets, leaks, 
neglect, poor installation, weakened threads, 
and wrong service. 

Careful, systematic maintenance will help 
prevent valve damage and destruction. 

Leaks 

Valves should be attended to at the first 
sign of a leak. 

Leaks may occur at the pipe-valve connec- 
tion, the valve seat, around the stuffing box 
and at the body-bonnet joint. 

Leaks waste fluid, and in cases of steam, 
for instance, they waste power and energy. 
A few examples of losses from leaks are 
given in the accompanying table. 

Another possible effect of leakage is that 



condensate may accumulate in the valve. If 
a valve in this condition is opened too rap- 
idly, the water hammer that may result can 
be so excessive as to damage the valve and 
piping and even injure the operator. 

Tightening a leaking joint will often correct 
the condition. Other remedies are the re- 
placement of gaskets or renewable parts, re- 
packing the stuffing box or regrinding seats. 

Improperly threaded connecting pipe may 
be the cause of leaks. Overly threaded pipes 
drawn against the interior may force the dia- 
phragm out of shape. 

Inspection 

Frequent and regular inspections are vital 
to careful and low-cost maintenance. Since 
adequate inspections often prevent the neces- 
sity of costly repairs, an inspection schedule 
should be set up and closely followed. The 
more often a valve is operated, the more fre- 
quent should be the inspections. 



229 



PLANT MAINTENANCE MANUAL 



LOSSES FROM LEAKS 



Leak Diam. 


Fluid 


Pressure 


Approx. 
Loss per Month 


1/32" 


Steam 


100 lb 


3,200 lb 


3/8" 


Steam 


100 lb 


460,000 lb 


1/32" 


Water 


40 lb 


4,800 gal 


3/8" 


Water 


40 lb 


690,000 gal 



Checking Valve Seat Leaks 

Inability to close the valve tightly, accom- 
panied by a pipe line leakage, is an indica- 
tion of a valve seat leak. Trouble of this sort 
is usually caused by scale, metal particles, 
or other foreign matter in the line. Some- 
times it comes from a cut in the seat or disc 
brought about by a high-velocity flow of the 
fluid through a limited area because the valve 
is not fully closed. This cutting action is called 
"wire drawing." 

Regrinding Seats on Globe 
and Angle Valves 

Discs or piugs of globe and angle valves 
that are cracked, cut, scored, or pitted should 
be repaired. 

If regrinding is practiced, use a fine-grained 
regrinding compound and follow the manu- 
facturer's instructions. 

If the seat is not scored too deeply, it may 
be resurfaced with emery cloth on a suitable 
mandrel. Where the cut is more serious, seats 
may be resurfaced with a valve reseating tool. 

In the case of check valves, follow the pro- 
cedures recommended for globe valves since 
the seating arrangements are similar. 

Replacing Worn Discs 

In valves of the renewable disc type, re- 
place the discs at the first sign of wear to 
assure longer life to the valves. In replacing 
discs, make sure that they are of the right 
composition for the service in which they are 
used. It is good practice to keep a supply 
of discs on hand. 

Resurfacing Gate Valve Seating 

For seat leaks in gate valves, remove the 
bonnet and inspect the gate. Resurface the 
gate very carefully with a fine emery cloth 
attached to a board, but only do so if the 
pitting or scoring is slight. 



Seating elements of the renewable kind 
which can no longer be resurfaced should be 
replaced. Where badly damaged seats can- 
not be replaced, they should be sent to the 
manufacturer for repairs. 

Repacking Stuffing Boxes 

Loose stuffing nuts and worn-out packing 
cause stuffing box leaks. Simply tightening the 
loose nut may correct the trouble in the first 
case. But when old or worn-out packing ma- 
terial is to blame, first open the valve wide 
open or close it (according to the type of 
the valve) before loosening the stuffing nut 
and taking off the gland. 

Remove the old packing from the stuffing 
box. Repack with packing recommended by 
the manufacturer of the valve or packing 
recommended by packing manufacturers for 
the service conditions. 

After replacing the gland, tighten the pack- 
ing nut enough to prevent leakage, yet per- 
mit easy spindle movement. Do not pull down 
the nut too tight. 

These practices apply to gate, globe, and 
angle valves alike, but not to the packless 
type of valve. 

Valve Records 

An orderly check-up of valves can be 
greatly facilitated by the use of suitable rec- 
ord forms. They are of particular value in 
connection with the inspection, repair, and 
replacement of valves. 

The forms list the parts of a valve and pro- 
vide spaces for recording the condition of 
each part and the material and labor costs 
of the necessary repair work. The total re- 
conditioning expense may be compared with 
the cost of a new valve, and if the former 
is a large proportion of the latter, replace- 
ment may be in order. 



230 



VALVES 



REGRINDING SEATS ON GLOBE AND ANGLE VALVES 




1. Stick a pin or nail through the 
hole in the lower portion of the stem, 
to lock the disc and stem together. 



2. Apply a good quality, fine-grain 
grinding compound with the finger 
to the seat and disc of the valve. 





3. Hold bonnet correctly in place and 
revolve hand wheel until the disc seats. 
Then raise bonnet 1/32" from body. 



4. Screw on bonnet ring to hand tight- 
ness. Then back it off about one turn. 
Oscillate hand wheel with one hand. 





5. After pitted surfaces are ground 
smooth, wipe seat and disc with cloth 
wet with gasoline or other solvent. 



6. When sure all grinding compound is 
removed, take out the pin from the hole 
in the shaft and reassemble the valve. 




231 



LUBRICATION 

Oil cans and grease guns can do much 
toward preventing valve troubles. Valves 
should be lubricated "on schedule." At least 
once a month is good timing. However, if 
valves are operated frequently, the moving 
parts should be lubricated more often. 

Oil or a combination of oil and graphite 
applied to the spindle just above the stuffing 
box keeps the stem and packing in good 
condition to resist frictional wear. Some valves 
have oil holes in the yoke cap. 

If the valve is provided with a grease gun 
fitting, that kind of lubricant is the one to use. 

Outside screw threads should be cleaned 
and lubricated systematically. 



Manufacturer Service 

When in doubt as to the best procedure 
to follow in repairing and reassembling valves, 
consult the manufacturer. Give him the figure 
number of the valve or a complete descrip- 
tion of it. Details should include the size, 
metal, composition, kind of seat, service in 
which used and a sketch, if possible. 

If valves are of the packless kind, it is also 
well to consult the manufacturer regarding 
their repair. In these valves diaphragms or 
bellows usually take the place of the spindle 
packing. 

There is a Right Valve for Every Service 
— Use the Right Valve in the Right Place. 




232 




CHA PTER 2 2 



TRAPS AND STRAINERS 



As everyone knows, steam is formed by 
adding heat to water. And when heat is re- 
moved from steam, the gas returns to water 
which is called condensate. Obviously then, 
the formation of condensate in steam lines 
and equipment using steam is a normal oc- 
currence. 

Compared to steam, however, water has 
little usable heat. So the removal of conden- 
sate from steam systems is most important. 

Steam traps are automatic valves that re- 
move and drain condensate from steam lines 
and from steam heating and processing appa- 
ratus with a minimum loss of steam to the 
system. Traps likewise prevent the waste of 
good steam by keeping it from emering the 
pipes that return the condensate to the 
boilers. 

Air dilutes steam also and the combination 
of air and water lowers the efficiency of 
steam. Air removal, therefore, is another im- 
portant function of a trap. 

Since steam traps prevent the waste of 
fuel, they help to reduce fuel costs in indus- 
trial plants. 

Typical Applications 

Traps are used in steam power plants, steam 
distribution systems and industrial steam pro- 



cesses. Typical applications are as follows: 
STEAM MAINS AND LINES 



To engines 
To turbines 
To pumps 

HEATING DEVICES 
Pipe coils 
Radiators 
Water heaters 



To compressors 

To process equipment 

For heating 

Room heaters 
Liquid heaters 
Blast coils 



Unit heaters 

PROCESSING APPARATUS 
Kettles and pans Plating and pickling 



Retorts 



tanks 
Autoclaves 



OTHER SPECIFIC EQUIPMENT 
Steam separators Drying cans (textile, 



and purifiers 
Air and gas 

purifiers 
Plastic presses 
Flash tanks 
Dry kilns 



paper) 
Cookers 
Steam tables 
Coffee urns 
Ironers 
Dryers 



KINDS OF TRAPS 

Steam traps are of two main kinds: 
Separating, and pumping steam or boiler 
return. 



233 



PLANT MAINTENANCE MANUAL 



The former take in the condensate at one 
pressure and discharge it to a lower pressure. 
The latter receive it at one pressure and dis- 
charge it against a higher pressure. This chap- 
ter will deal primarily with separating traps. 

Separating traps are of various types such 
as the following: thermostatic, bucket, float, 
float and thermostatic, and impulse. 

There are, of course, additional varieties 
of traps which include the following: thermal, 
tilting, labyrinth, orifice, baffle, thermodynamic, 
piston-operated, compound, combination, and 
so forth. 

Some of the common types of traps are de- 
scribed and illustrated in this chapter. Those 
mentioned show only a few of several possi- 
ble types of construction. They are used merely 
to illustrate in detail the basic principles of 
some real, rather than hypothetical, traps 
used in industry. 

Thermostatic Traps 

Thermostatic traps make use of the differ- 
ence in temperatures between the steam and 
the condensate to open and close the valve. 
The action of a metal bellows or diaphragm 
controls the discharge valve. 

In a representative trap of this kind, a tightly 



sealed bellows is partially filled with a volatile 
liquid. When the steam in the trap heats the 
bellows, the liquid in it boils creating a vapor 
pressure within the bellows. This pressure is 
slightly higher than that of the steam surround- 
ing the bellows. The expanding bellows closes 
the valve to prevent the escape of steam. 

When the condensate collects in the trap, 
the lowered temperature reduces the pressure 
in the bellows causing it to contract and open 
the discharge valve. These traps utilize the 
balanced pressure principle and work inter- 
mittently. 

Air is vented in the same way that the con- 
densate is discharged. The volatile liquid in 
the bellows condenses when the air surrounds 
it, and the reduction in pressure opens the 
valve and vents the air. 

No adjustment of these valves is necessary 
for pressure fluctuations. 

The liquid expansion' trap is another form 
of the thermostatic type. The thermostatic ele- 
ment of this trap is filled with a special oil and 
is sealed hermetically. When heat is applied 
to the trap, the oil expands and advances the 
plunger, thereby forcing the valve head on 
the plunger against the valve seat to close the 
valve again. 




234 



TRAPS AND STRAINERS 



Bucket Traps 



INVERTED BUCKET TYPES 

A very common form of trap of this kind is 
the one in which the bucket is inverted and 
submerged in the water. When steam enters, 
or is caught in the bucket, the bucket floats 
and closes the valve. As the water displaces 
steam, or the steam condenses, the bucket 
loses its buoyancy and sinks, thereby opening 
the discharge valve for the passage of the 
condensate. This cycle continues intermittently. 



Small amounts of air in the bucket escape 
through a small hole in the bucket and may 
be discharged to the return line with the con- 
densate or to the atmosphere. Two methods 
of exhausting larger amounts of air are through 
a manual by-pass or through a special bi- 
metal strip and disc arrangement that works 
by thermal or heat action. 

Buckets may or may not have center guides,- 
and sometimes the buckets are pivoted. 




UPRIGHT BUCKET TYPES 

Another kind of bucket trap has an upright 
bucket. When the water in the trap overflows 
into the bucket sufficiently to overcome its 
buoyancy, the bucket drops and opens the 
valve. The condensate is then forced through 
the vertical or siphon tube until enough water 
has been removed from the bucket to allow 
it to regain its buoyancy. The bucket then 
floats and closes the valve opening. An in- 
ternal by-pass is sometimes provided. 

With a vent hole in the discharge tube, an 
upright bucket trap can discharge some air 
every time the bucket sinks. If more air has to 
be handled, a pet cock or an auxiliary ther- 
mostatic device may be added. 




235 



PLANT MAINTENANCE MANUAL 




Float Traps 

In the float trap illustrated, the closed ball 
which floats on the condensate regulates the 
opening and the closing of the valve. As the 
level of the condensate rises, the float, con- 
nected to the discharge valve by a lever, 
opens the port further, giving it a greater dis- 
charge capacity. A lowering of the water 
level, and the ball with it, conversely restricts 
the passage of the condensate. As long as the 
valve is below the water level, the trap is 



auxiliary thermostatic trap supplies a means 
for the release of air— as is provided by the 
combined float and thermostatic kind of trap. 

Float and Thermostatic Traps 

In that combined trap, the float regulates 
the discharge of the water and the thermo- 
static element automatically disposes of the 
air and incondensable gases that reach the 
trap. 

In the type shown, the closed ball is con- 





water-sealed against the discharge of good 
steam. 

These traps are used where the drain of 
condensate is continuous, and there are sev- 
eral other varieties of them. 

Air may be removed from a float trap by 
means of a pet cock. Or the addition of an 



nected to the discharge valve by a lever 
mechanism. The level of the condensate in the 
irap determines the size of the opening in the 
discharge valve. This operation is the same as 
that of the float trap; and the air venting is 
the same as that in the thermostatic traps. 
These traps are continuous flow devices. 



236 



TRAPS AND STRAINERS 




Trap Installations in Steam Pipe Systems 



Impulse Traps 

The impulse trap takes advantage of the 
fact that when temperature changes occur in 
fluid flowing through two orifices in series 
with a closed chamber between them, these 
changes in temperature create pressure 
changes in the intermediate chamber. These 
variations in pressures are used to open and 
close the valve of this trap for the discharge 
of condensate and the prevention of loss of 
steam. 

In the impulse trap, the first orifice is the 
clearance around the control disc or piston of 
the main valve. The intermediate chamber is 
the closed space above the piston and the 
second orifice is the small hole in the center 
of the valve, leading to the outlet end of the 
trap. 

A small portion of condensate flows con- 
tinuously through the trap by way of the two 
orifices mentioned above, by-passing the main 
seat. When condensate temperatures are low, 
the discharge through the center of the valve 
reduces the pressure in the control chamber 
and the valve is lifted for full discharge through 
the main seat. When the heat of the conden- 
sate rises to near steam temperature, the re- 
duced pressure in the control chamber causes 



this hot water to flash into vapor and the in- 
creased volume chokes the flow through the 
valve center, building up pressure in the cham- 
ber and closing the valve to stop the dis- 
charge through the main seat. 

Small quantities of condensate pass through 
the control chamber and the valve does not 
lift. At medium condensate loads, the valve 
opens and closes at short intervals. For large 
amounts of condensate, the valve opens wide 
and the discharge is heavy and continuous. 




Strainers 

Strainers or dirt legs or pockets should be 
placed ahead of traps, reducing valves and 
other appliances, especially if dirt, scale, pipe 
cuttings and other foreign matter are present. 



237 



PLANT MAINTENANCE MANUAL 



SELECTION OF THE PROPER TRAPS 



The selection of the right trap for the spe- 
cific application is essential to efficient opera- 
tion and low cost maintenance because the 
use of the wrong trap can be the cause of 
much trouble. Troublesome errors in selecting 
a trap for a given job are those of picking a 
trap that is too small, that has insufficient air- 
handling ability, and whose working pressures 
are incorrect for the requirements of the in- 
stallation. 

The capacity of a trap depends upon its 
actual condensate handling ability; and in this 
respect care should be taken to make sure 
that a trap has sufficient capacity to handle 
the accumulations of condensate when start- 
ing up the system as well as when operating 
loads are at the peak. 

Before selecting a steam trap, determine 
the maximum amount of condensate that has 
to be handled, the air removal needs, any 
pressure fluctuations, and the pressure differ- 
ential or difference between operating pres- 
sures and back pressures. 

Some manufacturers rate their trap capac- 
ities according to actual tests of the amount 



of condensate a trap can handle— the tests 
being made with condensate at steam tem- 
peratures. Others may rate traps from hot 
water, or even cold water, tests. In testing 
traps continuous flow with valves wide open 
is considered even for traps that operate in- 
termittently. 

In selecting suitable traps it is common prac- 
tice to pick traps that can handle more water 
than the actual condensate requirements of 
the job. This capacity factor may be two— or 
it may be anything up to five or six, as the 
circumstances warrant. 

It is always well to consult with the manu- 
facturers for their experienced recommenda- 
tions. 

Traps are tested at the factory before ship- 
ment and are in first-class condition. So in 
order to get the best service possible from 
traps, be sure to follow closely the manufac- 
turer's instructions which accompany the traps. 
Makers also supply other literature which 
should be consulted for good practices in the 
installation, operation and maintenance of 
their traps. 



TYPCS Of /A/STAUA7/0MS 

STRAINER 




END OF 

STEAM MAIN A TRAP 

DRY RETURN 

TEAM 
EPARATOR 




DRAIN 



TRAP 
DISCHARGE 

«» STEAM 
X TRAP 




TRAP 



238 



TRAPS AND STRAINERS 



Installation 

Wherever possible traps should be installed 
at the low point and below— to provide gravity 
drainage— and as near as possible to the 
equipment they serve. Their location should 
also be easily accessible for inspection and 
maintenance because traps that are hard to 
get at are usually neglected. 

Generally speaking, it is good practice to 
supply each unit to be drained with a steam 
trap rather than to let a single trap serve two 
or more units. The latter situation may result 
in short circuiting. Air or condensate may 
collect in one machine, thereby lowering the 
temperature to below that of steam and thus 
reducing its operating efficiency. Also, since 
non-productive radiation losses are thus in- 
creased, excess steam is consumed, and extra 
labor costs incurred. 

If a trap must be located above the unit it 
serves, a check valve, or water seal, should 
be placed ahead of the trap at the low point 
in order to stop any back flow of the con- 
densate prime. A check valve may also be 
set in the trap. 

Check valves are used as well on the dis- 
charge side of the trap when condensate is 
discharged by pressure to a return above the 
trap so as to prevent condensate from flow- 
ing from the return back to the unit. 

Still another use for check valves is in a 
battery of machines wherein steam is admitted 
to all but one or two machines at the same 
time. Here check valves prevent condensate 



- — X - 




Is < 


I 








By 


Po 


LOIRT P0CKE1 
ss Arranger 


rient 



from backing up into and loading up the un- 
used units and their traps with water. 

Where by-passes are desirable or neces- 
sary to provide continuity of service, they 
should be installed. By-passes around traps 
facilitate the cleaning of the trap without hav- 
ing to shut down the apparatus. 

Test valves can be placed in the discharge 
line near the trap if traps are to be operated 
continuously. 

Pipe Connections 

The pipe connections to traps should be 
simple and direct. In laying out the piping 
system for best results, the advice of piping 
experts should be sought. 

Be sure that the connecting lines are large 
enough to handle the condensate. If too small, 
the pressure drop in the line and trap will be 
excessive, thus reducing trap efficiency. 

In some cases it may be advisable to install 
unions or nipples and valves on both sides of 
a trap to make removal of the trap easy. 

MAINTENANCE PRACTICES 

A good, profitable suggestion is to have 
on hand a few spare traps which can be used 
as replacements when traps go bad. The trap 
taken out of the line can be reconditioned 
and made readv for service as another spare. 

Although steam traps today are of modern 
design and strong construction, and give long 
efficient service, they are mechanical devices 
and need attention from time to time. Trap 
operations should be checked periodically, 
and the operating mechanisms of the traps 
should be inspected at least once a year. 

Cleaning 

One of the primary maintenance steps is 
the periodic cleaning of accumulated dirt. The 
frequency of this routine depends upon the 
service required of the traps and the condi- 
tions under which they operate. 

When traps are taken apart for cleaning, 
they should also be inspected for wear. Ex- 
amine seats to see that they are not plugged 
or worn. Check vent holes for stoppages. 

Traps with valves and other moving ele- 
ments may require the renewal of those parts 
from time to time. Gaskets, too, need periodic 
replacements. 

Before installing or starting traps, be sure 
to blow out the piping and apparatus thor- 
oughly with live steam in order to clear the 
system of scale, pipe threading chips, pipe 
joint cement, and other foreign matter. 



239 



PLANT MAINTENANCE MANUAL 



Priming 

When steam is turned on there is usually 
enough condensate in the line to prime the 
trap. In turning on the steam do so slowly so 
that the trap will catch the prime. Only bucket 
traps require priming. 

If prime is insufficient, the trap may be filled 
with water through an inlet connection, or 
through the test cock tapping. Another meth- 
od, where there is a valve on the discharge 
side, is to shut off that valve until sufficient 
condensate to prime the trap has accumulated. 

Make sure that the lines to the traps are 
clear, and blow them out if necessary. 

Steam Pressures 

Steam pressures should be checked at 
regular intervals, especially where regulating 
valves are used to control the steam supply 
to heating and processing equipment. 

If the pressure is too low, the apparatus 
may not be getting enough steam, and the 
traps may not drain satisfactorily because of 
insufficient differential in pressure. 

If the pressure is too high, the opening of 
mechanically operated traps may be difficult; 
and where traps are of the thermostatic type, 
damaging of the thermal element may result. 

Flash Steam 

The condensate in a steam trap is, of 
course, hot water,- and when the pressure on 
it is lowered suddenly, heat units are liber- 
ated and the water re-evaporates. This action 
is called flashing and it produces "flash 
steam." 

Flash steam should not be confused with 
live steam, which is often called "blue steam" 
and is accompanied by little or no conden- 
sate. Flash steam is more white in appearance 
and varies with the amount of condensate. 

A discharge of flash steam from a trap 
should not be mistaken for a leak or blow of 
live steam. 

Passing Steam 

Check cocks and gages for leakage. Where 
necessary, repair any parts. 

If pet cocks are used to vent air and to pre- 
vent air binding, be sure that only a minimum 
of steam is wasted to the atmosphere when 
opening them. 

Where steam is passed in traps of the baffle 
type, with condensate valves that are manually 
controlled, stop down the manual setting until 
steam no longer passes. 

If traps in a heating system pass steam, note 
the temperature of the trap return main. If the 
temperature is too high at the boiler room, 



look for hot runouts from stubs or risers along 
the returns. 

Where traps have by-passes, the by-pass 
valves should be checked for steam tightness. 

Do not leave by-pass valves open unneces- 
sarily because it wastes considerable amounts 
of steam. 

Trap Testing 

A regular schedule for testing traps should 
be instituted, if one has not already been 
adopted. 

Test valves or "T's" or "Y's" with pipe 
plugs may be used to facilitate testing for 
steam leaks. These valves should be located 
on the downstream side of the trap valve. 

In installations where the back pressure in 
the return line is high, a check valve or shut- 
off valve should be placed in the discharge 
line to keep flash steam in the return line from 
passing through the test valve. 

Lapping Valve Parts 

Where a trap has been in service for some 
time, it may be advisable to lap the valve and 
valve seat together. A breast drill can be used 
for that purpose, and the lapping compound 
should be of a fine grade. The weight of the 
drill alone is enough pressure in lapping, so 
do not lean on the drill or exert any addi- 
tional pressure on it. All traces of lapping 
compound should be removed after the lap- 
ping operation. 

Generally speaking, a new valve should not 
be used with an old seat, nor an old valve 
with a new seat. If new parts are to be intro- 
duced, both the seat and the valve should 
be renewed. 

Air Venting 

The mixing of air with steam lowers the heat 
value and efficiency of a steam system. Look- 
ing at it from another angle, heat transfer 
efficiency is affected by air mixed with steam, 
since air alone is a poor conductor of heat. 
Air which remains when steam condenses 
forms a sort of "insulation" next to the heat- 
ing surfaces. Thus, air mixed with steam also 
reduces the capacity of a trap. Furthermore, 
entrained air can keep the condensate from 
entering the trap, thereby preventing it from 
functioning properly. 

Some means to remove air from a trap and 
to prevent a trap from air-binding is essential 
in most installations. Devices for exhausting 
air and other incondensable gases from traps 
include pet cocks, vent holes, thermostatic or 
thermal action elements, or by-pass arange- 
ments, as noted in the discussions of the dif- 
ferent types of traps. 



240 



TRAPS AND STRAINERS 



GOOD TRAP PRACTICES 



Routine inspection schedules should be 
adopted and followed. At least once a year 
open and examine all traps and clean them 
thoroughly, and make all repairs necessary. 

To avoid injury to the bellows, thermostatic 
traps should not be opened when they are 
hot. Inspection of these traps, therefore, can 
be done more appropriately in the summer. 

A Special Committee of Steam Trap Manu- 
facturers prepared a "Waste Chasers Quiz" 
on good practices with regard to steam traps. 
It included the following question-and-answer 
procedures quoted below: 

a. is the trap body or mechanism dirty? 
Remove all sediment and other dirt from the 

trap body. Mechanisms may require cleaning 
by immersing in kerosene or other suitable 
cleaner. If there is an exceptional amount of 
dirt, it might be advisable to install ahead of 
the trap a strainer, which will have to be 
blown down or cleaned at periodic intervals. 
The presence of any oily paste in the trap 
body, particularly on traps draining lines sup- 
plied with exhaust steam from reciprocating 
engines, may indicate that the engine is get- 
ting an excessive amount of poor grade of 
oil. Check this point. 

b. Are valves and seats tight? 

If the valve seat has a sharp edge and if 



there is a narrow and shallow bright ring all 
the way around the valve, the chances are 
that the valve is making a tight joint with its 
seat. All valves and seats that have become 
wire drawn or badly grooved from wear 
should be replaced with new valve parts that 
have been properly lapped together. Be sure 
that the new valve parts are the right size for 
the trap and the operating pressure. 

c. Is the operating mechanism in good con- 
dition? 

Cracked or corroded buckets should be 
replaced. A closed float that is partly filled 
with water indicates a leak and the float 
should be replaced. 

Check the operating mechanism, or lever- 
age system for smooth operation. Any erratic 
action should be eliminated by repairing or 
replacing worn, corroded, or damaged parts. 

d. Is the air-venting mechanism in good con- 
dition? 

If trap buckets are equipped with an aux- 
iliary bi-metal thermostatic air vent, make sure 
that it is functioning properly by immersing in 
boiling water. 

In float and thermostatic traps, check the 
bellows valve and seat. 

Replace worn out bellows or worn valve 
parts. 




241 



PLANT MAINTENANCE MANUAL 





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242 



TRAPS AND STRAINERS 



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245 



PLANT MAINTENANCE MANUAL 



STRAINERS 



Strainers are used to protect steam traps, 
reducing valves and other items of pipe line 
equipment. They prevent dirt, scale, rust, chips, 
sediment and other foreign matter from clog- 
ging steam apparatus. 

Maintenance engineers, therefore, are ap- 
preciating more and more the economy of 
installing strainers for the protection of all 
kinds of steam units. Strainers may save many 
maintenance dollars. 

The screens are made of bronze, brass, 
stainless steel, monel, wire cloth, special 'al- 



loys, or of other corrosion-resistant materials. 
Strainers are supplied with clean-out plugs 
or blow-out, or blow-off connections. 

CLEAN STRAINERS REGULARLY. Cleaning 
is relatively simple. The screens are easily 
removed or blown-down. Blow-off lines have 
valves or shut-off cocks. Gaskets should also 
be inspected. 

Follow the manufacturer's instructions on the 
best way to use and clean strainers of his 
own make. 




FROM APPARATUS 
BEING DRAINFD 



STEAM TRAP 





STRAINER 




STRAINERS SAVE MANY MAINTENANCE DOLLARS, 



244 




CHAPTER 23 



FIRE EXTINGUISHERS 



Portable fire extinguishers are essentially 
"first aid fire devices . . . designed to cope 
with fires in their incipiency and are con- 
sidered necessary even though the property 
is equipped with automatic sprinklers or stand- 
pipe and hose". 

The more common kinds of portable ex- 
tinguishers are as follows: water pail, sand 
pail, pump tank, water type (gas cartridge), 
anti-freeze, loaded stream, soda-acid, foam, 
dry chemical, vaporizing liquid and carbon 
dioxide. Most first aid devices are of two 
forms: hand carried and wheeled. Size and 
capacity determine the form of portability. 
This chapter deals with the hand portable 
kind. 

KINDS OF FIRES 

Different kinds of fires act differently. Fur- 
thermore, all first aid appliances are not ef- 
fective against all sorts of fires that may 
occur in industrial plants. 

It is necessary to know, therefore, what 
kinds of extinguishers can, and should, be 
used to fight a certain class of fire. 

In order to provide a basis upon which to 
rate the relative fire-extinguishing values of 
the different kinds of first aid fire-protection 
appliances, the Underwriters' Laboratories, 
Inc., which is sponsored by the National 



Board of Fire Underwriters, has classified 
fires according to three general kinds: Classes 
"A", "B" and "C". These are described else- 
where. 

The Underwriters' Laboratories, Inc., has 
also determined the number, from 1 to 5, of 
the various capacity sizes of hand portable 
appliances that are required to make up one 
unit of First Aid Fire Protection. These stand- 
ards are cooperatively recommended by the 
National Fire Protection Association. 

Approved devices made by manufacturers 
of fire extinguishers bear labels showing that 
they have been inspected and tested by the 
Underwriters' Laboratories, Inc. and are suit- 
able for use in fighting a certain class or 
classes of fires and, for hand extinguishers, 
how many of a given kind and size comprise 
a first aid unit. 

The Factory Mutual Laboratories of the As- 
sociated Factory Mutual Fire Insurance Com- 
panies is another authoritative agency which 
tests and approves appliances for their suit- 
ability in extinguishing fires. Based on these 
tests, the Inspection Department of the Fac- 
tory Mutual organization issues Fire Rating 
Guides and Bulletins of Approved Equipment. 
The letters FM in a diamond on the product 
indicates approval by this group. 



245 



PLANT MAINTENANCE MANUAL 



FIRE CLASSIFICATIONS 



EXTINGUISHERS TO USE 




These are fires in ordinary combustible ma- 
terials such as wood, paper, textiles, rubbish, 
etc. Here the quenching and cooling effects 
of quantities of water, or of solutions con- 
taining large percentages of water, are im- 
portant elements in fire control. 



CLASS "B" FIRES 



Soda-acid, foam, pump tank, water type, 
loaded stream, anti-freeze, water pail and 
water hose. Vaporizing liquid, dry chemical 
and carbon dioxide are effective for control- 
ling small fires where there are no strong air 
currents. 



EXTINGUISHERS TO USE 




These are fires in small quantities of flam- 
mable and rapidly burning materials such as 
gasoline, oil or grease in vats or other open 
vessels or on floors. Important in extinguishing 
these fires is the blanketing or smothering ef- 
fects of the extinguishing agent which cuts off 
the supply of oxygen. 



CLASS "C" FIRES 



Foam, dry chemical, vaporizing liquid, car- 
bon dioxide and loaded stream. 



EXTINGUISHERS TO USE 




These are fires in electrical equipment. The 
extinguishing agent used for this type of fire 
must neither damage the electrical apparatus 
nor conduct an electric charge to the oper- 
ator along a liquid stream or the hose. 



Dry chemical, vaporizing liquid and carbon 
dioxide. Fog nozzles on water lines are also 
effective for low voltage (under 600 volts) 
fires. In some cases fires in electrical equip- 
ment may require the cooling and quenching 
effect of large quantities of water. The equip- 
ment should be electrically dead before water 
or water solutions are used. 



HELP KEEP YOUR PLANT 'FIRE SAFE" BY MAINTAINING 
YOUR FIRE PROTECTION EQUIPMENT IN GOOD CONDITION. 



246 



FIRE EXTINGUISHERS 



MAINTENANCE 



Responsibility for keeping an industrial plant 
safe from fires involves not only the providing 
of proper protective devices but also the edu- 
cating of employes in the correct use, care 
and maintenance of that equipment. 

All fire extinguishers display, and all manu- 
facturers of them supply, instructions on the 
correct and effective use, care and servicing 
of their devices. Follow such instructions at 
all times. 

Show employes how to handle and operate 
the various extinguishers and how to fight the 
different kinds of fires to best advantage. 
Give them demonstrations and practice in us- 
ing first aid equipment. 

By no means the least element in any fire 
protection program is to keep all equipment 
in first class condition, ready for instant and 
effective use when needed. 

The types of equipment required and the 
organization for fighting fires vary from plant 
to plant— but certain basic maintenance pro- 
cedures are common to practically all organi- 
zations and kinds of extinguishers. 

Extinguishers should be inspected frequently. 
They should be refilled immediately after use 
They should be thoroughly serviced at least 
once a year. 

INSPECT — once a week is not too frequent 
—to see that extinguishers are in their proper 
places and are easily accessible. 



EXAMINE PERIODICALLY -once a month 
or at least several times a year— to make sure 
that extinguishers have not been tampered 
with or injured by misuse. Check nozzles for 
clogging. 

Specific yearly servicing instructions are 
given later for each kind of extinguisher. At 
each annual inspection and servicing, it is 
recommended that one or more extinguishers 
be discharged in an actual fire-fighting dem- 
onstration for the benefit of the employes. 

Recharging and servicing should be done 
by experienced men. If it is necessary to em- 
ploy inexperienced persons for this work, 
make sure that they are properly supervised. 

When recharging or repairing fire extin- 
guishers, use only spare parts and materials 
supplied by the manufacturer of the particular 
device being serviced. Furthermore, when 
charging or otherwise maintaining first aid 
appliances be sure to follow carefully the 
directions on the extinguisher nameplate or 
recharging package. 

Another good maintenance practice to 
adopt in all cases is to date-tag an extin- 
guisher each time it is serviced or recharged, 
recording also the name of person doing the 
work. 

Additional maintenance steps are given in 
the various sections on the different kinds of 
extinguishers. 



WATER PAILS -WATER BARRELS -BUCKET TANKS 



fl 




| EFFECTIVENESS ^ 


CLASS "A" 


YES A 


CLASS "B" 


NO J 


CLASS "C" 


NO J 



These water extinguishers are effective on 
incipient Class "A" fires of wood, paper, 
textiles, rubbish and other ordinary combust- 
ible materials. They are NOT effective on the 
oil, grease or gasoline fires of Class "B". 
Neither are they recommended for Class "C" 



fires, particularly if they contain anti-freeze 
solution. 

The pails are carried by hand to the fire 
and the contents thrown or poured on the fire. 
The liquid can be directed to a maximum dis- 
tance of about 10 feet horizontally. 



247 



PLANT MAINTENANCE MANUAL 



The extinguishing agent is water, but where 
subjected to freezing conditions a solution of 
calcium chloride is used. Standards for suit- 
able anti-freeze solutions have been desig- 



nated by the National Board of Fire Under- 
writers, as recommended by the National Fire 
Protection Association. (See Table.) 



CALCIUM CHLORIDE SOLUTIONS FOR WATER PAILS AND HAND PUMP EXTINGUISHERS 

NOTE: This table based on granulated 75% calcium chloride 2y 2 Gallons Anti-Freeze Solution 

Freezing Temperature Water Calcium Chloride Specific Gravity Degrees Baume 

10° F 2 gal 1 qt 5 lb 1.139 17.7 

Zero F 2 gal 1 qt 6% lb 1.175 21.6 

10° below zero F 2 gal 7 lb 6 oz 1.205 24.7 

20° below zero F 2 gal 8 lb 6 oz 1.228 26.9 

30° below zero F 2 gal 9 lb 2 oz 1.246 28.6 

40° below zero F 2 gal 10 lb 1.263 30.2 



Units for First Aid Fire Protection 



Pails 

Five (5) standard pails (A-5).A standard pail 
has a 12-quart capacity and is made of gal- 
vanized iron or steel or of fiber, preferably 
with loose fitting cover to keep out dirt. 


00 
00 


Water Barrels 
(Casks, Drums, etc.) 

50-gallon cask or drum with loose fitting 
cover and with at least 2 or 3 standard fire 
pails in, attached to, or nearby it. (A-l). 




^^SlEEv^l 




Bucket Tanks 

25, 35 or 40 gallon tank with at least six 
10-quart, or larger, pails nested together un- 
der water in the tank. (A-l). 









Maintenance 

Examine containers at regular intervals — 
once a week is a good period, but never less 
than several times a year— to see that they 
have not been tampered with and that the 
water is not too dirty. Make sure that extin- 
guishers are properly placed and accessible. 

Keep pails, barrels, casks, drums and tanks 
full at all times by replacing liquid that has 
evaporated. Change liquid if it has become 
very dirty or foul. 

Refill containers as soon as possible after 
using. 

Inspect containers at least once a year for 



deterioration, misuse or injury. Replace those 
not in good condition. 

If anti-freeze solutions are used, check the 
specific gravity in order to insure against 
freezing at lowest temperatures to be en- 
countered. Recharge, if necessary. 

Keep on hand in airtight receptacle some 
granulated or flake calcium chloride for refill 
purposes. 

Chemicals — copper sulphate in proportions 
of 1 part to 10,000 — may be used to keep 
water from fouling. If chemicals are so used, 
the inside of the containers should be suitably 
protected against corrosion. 



248 



FIRE EXTINGUISHERS 



PUMP TANKS 



EFFECTIVENESS UNIT OF FIRST AID PROTECTION 



KIND 
OF 
FIRE 


CLASS "A" 


YES 


2'/ 2 gal. j 

4 gal.j A-l 

5 gal.' 


CLASS "B'" 


NO 


CLASS "C" 


NO 


Maximum Horizontal Range. 


.... 30 to 40 feet 


y 



EXTINGUISHING AGENT: Water; or where 
freezing conditions are encountered, anti- 
freeze solution of calcium chloride according 
to table in "Water Pails" section. Expel by 
pumping. 

OPERATION OF HAND TYPE: Carried to fire 
by handle on tank, or pump handle if it has 
locking hinge. 

At fire, place tank on floor or ground 
and put foot on rest at bottom of tank. Pump 
with one hand and direct stream with other. 
If two men, one pumps while the other directs 
stream. Pump vigorously and with full stroke. 

Direct stream at base of flames, approach- 
ing from windward side. Move around fire, if 
possible. 



I 



Maintenance 

Follow basic maintenance requirements set 
forth at beginning of this chapter. 

Keep tank full— water or solution up to fill- 
ing mark— at all times. 

Recharge with water or solution as soon 
as possible after use. This kind of extinguisher 
can be filled while in use. 

Operate the pump periodically— once each 
month should be frequent enough. The water 
or anti-freeze solution can be returned to the 
tank by introducing the nozzle through the 
filler cap opening. 

Oil pump shaft occassionally, working pump 
to distribute oil. 

Service completely once a year. Discharge 
contents of pump. 



Examine pump and its parts, including gas- 
kets and hose. Replace parts not in good con- 
dition. 

Clean and flush tank, hose and nozzle with 
water. Refill with water or anti-freeze solu- 
tion. Make sure filler cap is tight. 

In servicing and recharging pump tanks 
containing anti-freeze some additional pre- 
cautions should be observed. These special 
procedures are presented in the section on 
"Anti-Freeze Extinguishers." 




Clean and flush 
tank with hose 



Return solution to 
tank when testing 




249 



PLANT MAINTENANCE MANUAL 



WATER TYPE (GAS CARTRIDGE) EXTINGUISHERS 



EFFECTIVENESS I UNIT OF FIRST AID PROTECTION 



CLASS •A" 


YES 


2% gal. A-l 


CLASS "B 


NO 


CLASS "C" 


NO 


Maximum Horizontal Range 30 to 40 feet 


J 



EXTINGUISHING AGENT: Water, which is 
expelled by expanding carbon dioxide re- 
leased from a metal cartridge set in the con- 
tainer. (If non-freezing properties are neces- 
sary, use "Anti-Freeze" extinguisher of this 
type.) 

OPERATION OF HAND TYPE: Carry to fire 
in upright position by ring cap. 

At fire, turn appliance up-side-down, hold- 
ing it by the bottom handle. Bump head on 
floor or ground so that the pin will puncture 
the metal cartridge to release the gas which 
is under pressure in the cartridge. 

From windward side of fire, direct stream at 
base of flames. 



Maintenance 

Follow basic maintenance procedures com- 
mon to all kinds of extinguishers, as set forth 
at beginning of this chapter. 

Recharge immediately, and only, after use. 
Unscrew ring cap. Remove cartridge. Clean 
appliance thoroughly by flushing it with water. 
Refill to mark on container. Insert new car- 
tridge. 

Service completely once a year. Test and 
examine extinguishers inside and out. Water 
should be at full mark on inside. Look at 
gaskets and puncturing pin. Lubricate ring-cap 
threads. 

Remove and examine cartridge. Weigh it 
to detect any loss of carbon dioxide pres- 
sure. If weight shows a loss of V2 ounce, or 



more, from original weight indicated on cart- 
ridge, replace it with a new one. Replace 
cartridge also if it is corroded, punctured, or 
otherwise damaged in any way. 

Use only cartridges supplied by the manu- 
facturers of the extinguishers in which they 
are to be inserted. Keep several cartridges 
on hand for replacement or recharging pur- 
poses. 

Used and damaged cartridges may be re- 
turned to the manufacturer for exchange or 
reloading. 




Flush with water 
after use 



Remove and 
examine cartridge 




250 



FIRE EXTINGUISHERS 



SODA AND ACID EXTINGUISHERS 



EFFECTIVENESS I UNIT OF FIRST AID PROTECTION 



KIND 

OF 

FIRE 


CLASS "A" 


YES 


P/2 gal.J 
2V 2 gal. A-1 


CLASS "B" 


NO 


CLASS "C" 


NO 


Maximum Horizontal Range. 


.... 30 to 40 feet 


s 



EXTINGUISHING AGENT: Solution of pow- 
dered bicarbonate of soda in the tank or 
shell and concentrated sulfuric acid in a bot- 
tle set in a cage positioned in the extin- 
guisher. Mixing of the acid with the solution 
generates carbon dioxide gas which expels 
the liquid. Subject to freezing. 
OPERATION OF HAND TYPE: Carry to fire 
by top handle. 

At fire, tip up-side down and hold by bot- 
tom handle. Inverting drops stopper out of 
acid bottle, mixing acid with the sodium bi- 
carbonate solution. 

From windward side, direct stream at base 
of flames, moving around fire if necessary. 



Maintenance 

Follow general maintenance procedures 
given earlier in the chapter. 

Keep full at all times, inspecting frequently 
to make sure. 

Recharge promptly after use. Remove cap 
and acid bottle and cage. Wash all parts 
with water and drain water through hose. 

Mix chemicals and water in separate recep- 
tacle outside extinguisher, following directions 
on the appliance or the package containing 
the soda. Be sure that the powdered chemi- 
cals are completely dissolved in warm water. 
Pour solution into shell and fill with water up 
to full mark. 

Insert recharged acid bottle in cage and 
position in tank. Recharge only under capable 
supervision. Use only recharges supplied -by 
the manufacturers of the extinguishers. 



Service thoroughly once a year. Empty by 
discharging and then recharge. Inspect com- 
pletely. 

Examine extinguisher and parts, including 
gaskets, for deterioration or damage from 
misuse, and check nozzle for clogging. Any 
parts or complete appliances which are not 
in good condition should be replaced. 

For prompt recharging and servicing, keep 
on hand a supply of chemical charges suitable 
for the particular manufacture of extinguishers 
used. 




Drain water through 
hose and nozzle 



Follow directions 
on soda package 




251 



PLANT MAINTENANCE MANUAL 



ANTI-FREEZE EXTINGUISHERS 



EFFECTIVENESS UNIT OF FIRST AID PROTECTION 



CLASS "A" 


YES 


2% gal. A-1 


CLASS "B" 


NO 


CLASS "C" 


NO 


Maximum Horizontal Range 30 to 40 feet J 



Where low temperatures are encountered, 
water-filled extinguishers are not suitable. 
For operation at freezing temperatures, as low 
as minus 40 F, special anti-freeze charges are 
used. 

EXTINGUISHING AGENT: Chemical solution 
of non-freezing properties, commonly having 
a calcium chloride base and anti-corrosion 
components. A cartridge secured in the tank 
contains carbon dioxide under pressure. 
When the cartridge is punctured, the expand- 
ing gas expels the liquid. 

A fuse type cartridge is also used in ex- 
tinguishers of this sort. The fuse is ignited by 
a firing pin, and in burning it develops a gas 
pressure which expels the liquid. 
OPERATION OF HAND TYPE: Carry to fire 
in upright position by top handle. 

At fire, invert and bump on floor to punc- 
ture gas cartridge or ignite fuse cartridge. 
Hold by bottom handle. 

Direct stream at base of flames. Start from 
windward side, and work around fire, if nec- 
essary. 



Maintenance 

The general procedures common to all 
kinds of extinguishers and those given for 
water-filled appliances apply to anti-freeze 
devices. 

Keep full at all times— inspect frequently to 
check this point. 

Recharge immediately after use. Remove 
solution from hose to prevent clogging. Wash 
with water and drain water through hose. 

Dissolve chemicals thoroughly in water, 
preferably warm, outside the container. They 
should never be mixed inside the tank. Be 
sure to follow manufacturers' directions which 



are stated on the extinguisher or the charging 
unit. Pour solution into shell through a fine 
strainer. Fill up to full mark. 

Once a year inspect and service thorough- 
ly. Solutions should be emptied into non-cor- 
rosive pails or other receptacles and checked 
for proper specific gravity. If solution still 
indicates satisfactory resistance to freezing, 
it can be poured back into the extinguisher. 
Otherwise use new solution. Lubricate threads 
of ring cap. 

Examine interior for corrosion and sediment 
and clean hose and nozzle. 

Always keep on hand a number of anti- 
freeze charges. Use only those supplied by 
the manufacturers of the extinguishers. 




Use charge supplied 
by manufacturer 



Inspect and 
service thoroughly 




252 



FIRE EXTINGUISHERS 



LOADED STREAM EXTINGUISHERS 



EFFECTIVENESS UNIT OF FIRST AID PROTECTION 



KIND 
OF 
FIRE 


CLASS "A" 


YES 


1 gal. A-2, B-4 
2V2 gal.) 




CLASS "B" 


YES 


CLASS "C 


NO 


Maximum Horizontal Range. 


30 to 40 feet 


y 



EXTINGUISHING AGENT: Alkali-metal-salt 
solution, commonly potassium carbonate and 
special salts. In many extinguishers of this kind 
a cartridge of carbon dioxide held inside the 
tank near the top is punctured to release the 
high pressure gas and expel the liquid. A 
chemical reaction is also used to expel the 
solution in some cases. 

OPERATION OF HAND TYPE: Carry to fire 
by top handle. 

At fire, operate according to instructions 
given on the extinguisher. If of cartridge type, 
invert and bump head on floor or ground to 
puncture cartridge. 

Play stream at base of flames and walk 
around fire if possible to reach it from all 
sides. 



Maintenance 

Follow general procedures given at the 
beginning of the chapter. 

Inspect frequently to see that extinguishers 
are full. The way to tell if a cartridge is fully 
charged is to weigh it. (See below.) 

Recharge immediately after use. Remove the 
old cartridge. Wash all parts thoroughly with 
water and drain water out through the hose, 
making sure that all water is removed to 
prevent clogging. 

If chemicals are not supplied in solution 
form, dissolve them thoroughly in water. The 
mixing should be done outside the tank. Fol- 
low manufacturers' instructions in preparing 
the solution and use only chemicals and cart- 
ridges supplied by the maker of the extin- 
guisher. After filling with new solution, insert 
new cartridge. 



Service yearly. Examine extinguisher and 
parts, including gaskets, for deterioration or 
injury from misuse. See that hose nozzles are 
not clogged. Replace all parts not in good 
condition. 

Remove cartridge and examine for condi- 
tion. Weigh it to detect any loss by leakage. 
If loss is more than one-half an ounce from 
the weight shown on it, replace with new 
one. 

Keep on hand a supply of cartridges and 
special chemical charges for the prompt re- 
charging of devices. 




Keep record 
on recharge tag 



Weight cartridge 
to detect leakage 




253 



PLANT MAINTENANCE MANUAL 



CLASS "A' 



CLASS "B' 



CLASS "C 



FOAM EXTINGUISHERS 



EFFECTIVENESS I UNIT OF FIRST AID PROTECTION 



YES 



YES 



NO 



P/4 90, J A 2 B2 
1 Vi gal. J A ' 2 ' B " 2 



Maximum Horizontal Range 30 to 40 feet 



EXTINGUISHING AGENT: A foam resulting 
from a chemical reaction of two solutions. 
Bicarbonate of soda and a foam stabilizing 
agent, and sometimes a preservative, are 
placed in the main tank. A solution of alumi- 
num sulfate is contained in an inner cylinder. 
Mixing these two chemicals creates and ex- 
pels the foam. Although this type of extin- 
guisher is subject to freezing, anti-freezing 
ingredients should not be used in it. 
OPERATION OF HAND TYPE: Carry to fire 
upright by top handle. 

At fire invert to mix chemicals, holding by 
bottom handle. 

Direct stream at base of flames. Use force 
of stream or coat burning surface. On flam- 
mable liquid fires in containers, direct dis- 
charge against wall just above burning sur- 
face. Work around fire if necessary. 



Maintenance 

Follow general maintenance procedures 
mentioned at the start of this chapter. 

Recharge immediately after use, and an- 
nually also. Remove inner container and stop- 
ple. Clean carefully with water, washing out 
extinguisher to remove foam or salts, draining 
water through hose and nozzle. 

Mix chemicals with water in a clean pail of 
other receptacle outside the extinguisher. 
Lukewarm water is preferable. Follow direc- 
tions on appliance or the charge package. 
Make sure chemicals are thoroughly dissolved 
before putting into tank. Use only chemical 
charges supplied by the manufacturer of the 



extinguishers and keep a supply of them on 
hand. 

Fill shell and inner chamber with solution 
up to proper level mark. Position inner con- 
tainer in place, seat stopple and screw down 
cap. 

Service the extinguishers completely at least 
once a year. Examine devices and all parts 
for deterioration and damage from misuse 
and for clogging of nozzles. Replace all 
items, including gaskets, which are not in 
good condition. 

Empty and recharge, as described above. 
This work should be done by experienced 
persons, or at least under capable supervision. 




Discharge and recharge 
once a year 



Stir briskly while 
adding chemical 




254 



FIRE EXTINGUISHERS 



VAPORIZING LIQUID EXTINGUISHERS 



EFFECTIVENESS I UNIT OF FIRST AID PROTECTION 



CLASS "A" 


No. but will 
control small fires 


L qt " )d o i go'- "\ o o 


CLASS "B" 


YES 


1 % qt. / B-2 » 1 B-2, 


CLASS "C" 


YES 


Max. Horizontal Range — 20 to 30 feet. S 



EXTINGUISHING AGENT: A special non- 
conducting liquid, the base of which is car- 
bon tetrachloride. The chemical has been 
treated with compounds to remove corroding 
impurities and to lower the freezing point. The 
liquid vaporizes into gas by the heat of the 
fire. Expulsion of the liquid is by pump action, 
air pressure or carbon dioxide pressure. 
OPERATION OF HAND TYPE: Use varies ac- 
cording to the mode of operation, so follow 
instructions shown on the extinguisher. 

If hand pump, for example, carry to fire 
by top handle. 

At fire, hold extinguisher in one hand and 
turn handle and pump vigorously with the 
other. 

Direct stream according to instructions for 
the kind of fire being fought. If ordinary Class 
"A" fire, direct stream at base of flames. If 
fire is of flammable liquids in a container, 
play stream against inside wall just above 
burning surface. If spill fire, start at nearest 
windward side and advance sweeping out 
fire. 



Maintenance 

Follow general maintenance procedures 
common to all extinguishers, as set forth at the 
beginning of this chapter. 

Keep extinguishers always full— but do not 
over-fill— and in good operating condition. 
Once a month lift them off holders to see that 
they are full and in good condition. 

If appliance is of the air-pressure kind, in- 
spect weekly to make sure the pressure is 
correct and that goges functton properly. 



Refill immediately after use; also if found to 
be partly empty. Extinguishers need not be 
discharged completely before filling. 

Unscrew filler cap, insert funnel in opening 
and pour in vaporizing liquid up to full mark. 
Replace cap. 

At least once a year, service extinguishers 
carefully; but recharging at this annual peri- 
od is not necessary. Examine for condition of 
pump and pressure and for deterioration or 
injuries. Look for corrosion in pump parts and 
washers. Extinguishers and parts not in good 
condition should be replaced. 

Test also by partial discharge of contents 
into a clean glass receptacle from which the 
liquid may be returned +o the tank. Refill to 
replace any lost liquid. 

Recharge only with liquid furnished by the 
manufacturer of the extinguisher, and keep 
on hand a supply of the special liquid for 
prompt recharging. 

Do npt use water in any way with these 
devices. 




Partially discharge 
into glass receptacle 



Refill at once after using 
or testing 




255 



PLANT MAINTENANCE MANUAL 



DRY CHEMICAL EXTINGUISHERS 



EFFECTIVENESS UNIT Ol 



D PROTECTION 



CLASS "A" 




No, but will 
control small flrei 




4 lb. 
10 lb. 

15 lb.} 
20 lb. ( 
30 lb. / 


B-2, C-2 ' 
B-2, C-'l 

B-1,C-1 


CLASS 0, B" 


YES 


\ CLASS "C" 


YES 






- 8 to 1 2 feet. 






Max. Horizontal Range - 


y 



EXTINGUISHING AGENT: A special prep- 
aration of bicarbonate of soda in dry powder 
form treated to make it flow and resist mois- 
ture. It is non-freezing and will not conduct 
electricity. The expellent is carbon dioxide in 
a cartridge in the hand type and nitrogen in. 
the wheeled. The discharge is a cloud or dust 
stream which smothers fire. 
OPERATION OF HAND TYPE: Carry to fire 
by top handle. 

At fire, keep upright. Pull out locking pin 
and turn hand wheel to left to puncture pres- 
sure cartridge and open nozzle. 

Direct stream at base of flames and worfc 
from side to side to sweep flames. Follow in- 
stuctions on extinguisher. 



Service extinguishers annually. Inspect them 
and all parts, including the hose, for deteri- 
oration or misuse. Replace all parts and ex- 
tinguishers not in good condition. See that 
chemical is in good, freely running condition 
and check hose for obstructions. 

At this annual inspection it is not necessary 
to recharge appliances. 

Use only the chemicals and cartridges sup- 
plied by the manufacturer. Keep a supply of 
these materials on hand for prompt recharg- 
ing. 

Never use water in any way with these ex- 
tinguishers. Also do not oil or grease nozzle 
parts,- polish them with fine emery cloth. 



Maintenance 

Observe general maintenance practices sug- 
gested at the beginning of the chapter. 

Keep full of chemicals at all times and make 
sure that cartridge is fully charged. Check 
cartridge twice a year by weighing. If loss 
of weight exceeds one-half ounce under ori- 
ginal weight stamped on cartridge, replace 
with a new one. 

Refill immediately after use, even if only 
partially emptied. Follow printed instructions 
closely and completely. 

Invert extinguisher and open nozzle to clear 
hose of chemical and to release pressure. 
Remove plug at bottom of tank and add dry 
chemical up to full indication. Replace plug. 

Stand tank upright and remove old cart- 
ridge, replacing it with a new one. 




Remove plug and 
fill with chemical 



Check cartridge 
weight semi-annually 




256 



FIRE EXTINGUISHERS 



CARBON DIOXIDE EXTINGUISHERS 



1 EFFECTIVENESS UNIT OF FIRST AID PROTECTION^ 


CLASS "A" 


No. but will 
control small fires 


2 lb. B-4 7i/ 2 lb."(B-2A 
2 lb.*) 10 Ib.jC-l 
4 lb. ( M f C-2 15 lb.\B-l, 
20 IbjC-l 
♦Special Control Valve 


CLASS "B" 


YES 


CLASS "C" 


YES 


Max. Horizontal Range — 3 to 8 feet. ^/ 



EXTINGUISHING AGENT: Carbon dioxide, 
which is non-injurious, non-corroding, non- 
freezing and non-conducting. At normal tem- 
peratures it is in liquid form. When discharged 
through the valve and a cylindrical nozzle or 
cone-shaped horn, the chemical expands and 
vaporizes into a cloud of gas and some 
"snow" which smother the fire by cutting off 
the oxygen. 

OPERATION OF HAND TYPE: Carry to fire 
by top handle. 

Work at fire according to instructions on 
extinguisher and the kind of control and valve 
action. 

From windward side, direct discharge at 
base of flames. Sweep flames off burning sur- 
face by moving cone from side to side and 
progressing forward. Continue discharge even 
after fire is out to prevent possible reflashing. 



Maintenance 

Observe general maintenance recommen- 
dations given at the beginning of this chapter. 

Recharge extinguishers promptly after use, 
even if only partly discharged. Unless suitable 
recharging equipment is available, return ex- 
tinguishers to the maker, his local agent or 
the manufacturer of carbon dioxide. If re- 
charging is to be done on the premises, be 
sure that facilities are complete and are main- 
tained in readiness for use. Also keep on 
hand a sufficient supply of commercial gas 
cylinders. 

Care should be taken to see that extin- 
guishers are full at all times. 



Check extinguishers twice a year by weigh- 
ing as directed on the appliance. If weight 
shows a loss of 10% or more of the rated 
capacity, recharge as directed above. 

At least once a year inspect devices for 
deterioration or injury from misuse. Replace 
parts or extinguishers not in good condition. 

It is not necessary to recharge at these 
periodic examinations if the devices are full 
of chemicals. But it is usually advisable to 
discharge one or more extinguishers in a fire 
fighting demonstration for employes— a pro- 
cedure which has been suggested for all 
kinds of extinguishers. 




Check extinguisher 
at least once a year 



Recharge when weight 
shows loss of 10% 




257 




CHAPTER 24 



AIR COMPRESSOR EQUIPMENT 



Compressed air is one of the major tools 
of industry. Its versatile power meets a wide, 
almost limitless, variety of industrial uses in 
the mills and factories of the nation. It is 
labor-saving, flexible and easily transmitted. 

A compressed air plant comprises one or 
more compressors with the necessary driver 
and control or regulator, intake air filter, after- 
cooler, air receiver, interconnecting piping 
and the proper distribution system to transport 
the air to the points of use. 

Compressors are machines for compressing 
air or gas from an initial intake pressure to 
a higher discharge pressure. They are made 
in various types or classes. 

Compressors are generally classified as to 
whether they are of the positive displacement 
or the dynamic type. 

In positive displacement compressors "suc- 
cessive volumes of air are confined within a 
closed space in which pressure is increased 
as the volume of closed space is decreased." 
Both reciprocating and rotary types are in- 
cluded in this group. In reciprocating com- 
pressors the compression element is a pis- 
ton while in rotary units the positive action of 
rotating elements provide the compression. 



In the dynamic type the "air or gas is 
compressed by the dynamic action of rotat- 
ing vanes, imparting velocity and pressure to 
the flowing medium. The velocity head is con- 
verted into pressure by diffusion." This kind 
of compressor includes the centrifugal and 
axial and mixed flow varieties. 

Plants may have a centralized air compres- 
sor installation or have separate units situated 
in departments or other localized areas. 

The Compressed Air and Gas Institute has 
published a comprehensive "Compressed 
Air Handbook" which covers Applications, 
Equipment and Engineering Data and Test 
Procedure. Considerable new and timely ma- 
terial on approved maintenance practices for 
compressed air equipment from this source has 
been made available for use here by the 
Institute. 

Installation 

For effective operation, a compressed air 
installation must provide a sufficient amount 
of air at sufficient pressure. A thorough study, 
therefore, should be made of any project in 
order that future, as well as present, needs 
are considered. That is, provision should be 
made for some excess capacity for growth. 



258 



AIR COMPRESSOR EQUIPMENT 



The analysis recommended takes into ac- 
count the following elements: 

a. Necessary compressor capacity. 

b. Number of units. 

c. Location of units. 

d. Regulation of compressed air plant. 

e. Air distribution system. 

Compressor Capacity 

In studying compressed air requirements of 
a plant, it will be found that some air devices 
operate almost continuously while others oper- 
ate infrequently. Some of these latter, how- 
ever, use large amounts of air while in oper- 
ation. Furthermore, the quantities of air re- 
quired by individual devices may vary ac- 
cording to the different uses to which they 
are put. 

One of the first things to do then is to de- 
termine the average air consumption of the 
air operated tools. Air, incidentally, is meas- 
ured in terms of cubic feet per minute of 
actual free air. This data may be obtained 
from the manufacturers of the actual tools. It 
should be remembered that all air-operated 
devices do not consume maximum amounts of 
air under all conditions. Since many tools 
operate intermittently, their "net air consump- 
tion" is much less than their maximum. 

It is necessary, therefore, to consider the 
Load Factor which is the ratio of the amount 
of air actually consumed to the maximum 
continuous full load air consumption. This Load 



Factor is made up of the Time Factor and the 
Work Factor. The former is the "percentage 
of the total time that the device actually uses 
air." The latter is the "per cent of the maxi- 
mum possible work output per minute." For 
example, even where a grinder is operating 
under full throttle, the air consumed depends 
upon the pressure exerted by the operator 
against the work. 

Studies show that the actual air consumed 
is only a relatively small fraction of the full- 
time rated air requirements. It is always best 
to consult with the tool manufacturer regard- 
ing the actual air needs. For the sake of 
general information, however, a table show- 
ing the approximate number of tools that 
can be operated by various sized compressors 
is given later in this chapter. 

In some instances, 10% allowances have 
been made for pipe leakage. Any waste of 
air, however, should not be condoned any 
more than the waste of any gas or other 
fuel, for air lines can be made and main- 
tained as tight as any other pipe line. 

One good indication that a plant is over- 
loaded and needs more compressor capacity 
is "low air pressure." Since low pressure re- 
duces production, it will be discussed in more 
detail later. Full air pressure at all working 
positions ensures maximum tool effectiveness 
and production — so maintain the right pres- 
sure at all times. 




259 



PLANT MAINTENANCE MANUAL 



TEN HELPFUL SERVICE HINTS 



1. Schedule and observe periodic inspec- 
tions. 

2. Check system for air leaks in pipe 
lines, valves and connections. 

3. Keep machine clean at all times. 

4. Check oil level in crankcase and lubri- 
cators. 

5. Use good grades of reliable lubricants. 

6. Check water cooling temperatures. 

7. Maintain equipment in good working 
order. 

8. Check safety valves. 

9. Inspect valve assemblies regularly. 
10. Keep intake filter clean. 



Number of Compressor Units 

Another important consideration is to deter- 
mine the number of units into which the total 
capacity should be divided. Manufacturers 
can give valuable advice on this point. 

Among the points to remember is the one 
that many plants need- small amounts of air 
at all times — including week ends and holi- 
days — for such devices as dry pipe sprinkler 
systems, oil burners and furnaces and air tools 
for plant maintenance requirements. It may 
also be necessary occasionally to take com- 
pressors out of service for maintenance or 
other attention, and standby units should be 
available for such times. 



Location of Compressor Units 

Compressor equipment is commonly housed 
in one centralized location. If the piping costs 
for the suitable distribution of air and the 
maintenance of pressure from one source are 
excessive, the compressor plant may be di- 
vided into two or more installations located 
near the specific load centers. Separate units 
may also be installed in different departments 
either as sources of prime power for that 
section or as auxiliary equipment. 

Under no circumstances should equipment 
be placed in obscure spots where apparatus 
is liable to be neglected. 



Compressed Air Distribution 

One of the most important elements in a 
compressed air installation is the distribution 
system because any pressure loss between the 
compressor and the point where the air is 
used is detrimental to most efficient operation 
of the system. The following conditions should 
be observed: 

a. Use pipes large enough to keep the initial 
pressure from dropping more than 10% 
between the receiver and point of use. 

b. Use a loop system for two-way distribution 
to points of greatest air demand. 

c. Locate proper receivers near the far ends 
and at points of heavy use on long distribu- 
tion lines. Such storage capacity avoids 
excessive drops. 

d. Supply each header or main with frequent 
outlets for attaching hose for air-operated 
devices. Outlets should be at the top of 
the pipe line to keep moisture from entering 
the tools. 

e. Slope all piping toward a drop leg or trap 
for the. removal of moisture from the system. 
The most suitable kind of power — elec- 
tricity, steam oil, gas or gasoline— should be 
determined. 

Manufacturers of compressed air equipment 
should be consulted for their experienced 
recommendations regarding the particular 
kind of units to use. 



260 



AIR COMPRESSOR EQUIPMENT 



RECIPROCATING COMPRESSORS 



In reciprocating compressors a piston com- 
presses the air or gas. This type is classed 
according to whether it is — 

a. Stationary— mounted on more or less 

permanent foundations. 

b. Portable — mounted on wheels for easy 

portability. 

c. Semi-portable — mounted on skids for 

portability. 

Stationary Type 

Locate equipment in a clean, dry, well- 
lighted area with sufficient space round it for 
cleaning, inspecting and dismantling. If the 
temperature drops well below freezing, the 
room should be heated. Where operating 
conditions are dusty, the compressor should 
be located in the main engine room or in a 
dust-tight room with provisions for drawing 
clean air into the system. 

Foundations of appropriate mass and base 
area for good subsoil are essential. Manu- 
facturers of compressors furnish drawings of 
suitable foundations for their compressors. 
Subsoil characteristics may be detemined by 
borings — at least four in number, one near 
each corner. Sometimes a concrete mat is 
required below the foundation block. Both 
the foundation block and the mat should be 
cast in a single pour. However, either may 
be poured separately; but if they are, anchor- 
ing together by vertical bars is necessary. 

To prevent vibration from the compressor 
being transmitted to the floors and walls, the 
latter should be insulated from the former. 

Maintenance 

Air filters must be used on the intake of 
every air compressor in order to keep dirt 
and grit out of the machine. Check and clean 
these filters occasionally. 

Before starting the machine, clean the suc- 
tion lines to remove the grit, pipe scale, sand 
and other foreign matter. 

Pipe lines carrying hot air should be kept 
clean to prevent a fire starting in the accumu- 
lated dirt and oil. 

Inspections should be scheduled at regular 
intervals. At these examination periods, worn 
parts should be replaced; new packing in- 
stalled; adjustments made for wear of parts,- 
and air valves and crankcases cleaned. 

Deposits on valves indicate dirty intake 
air or the use of too much, or unsuitable, oil. 



Examine ports and passages and remove 
carbon, sticky oil and other obstructions. 

Inspect water jackets. Wash them out as 
often as the condition of the water makes it 
necessary. 

Change the crankcase oil at regular inter- 
vals. After drawing off the oil, clean the 
crankcase thoroughly, making sure that no 
shreds of lint remain to clog up oil passages. 
Waste should not be used for wiping out the 
crankcase. Neither should gasoline or other 
inflammable liquid be employed for washing. 

As many as three types of oil may be re- 
quired in a compressor: one for the com- 
pressor cylinder, a second for the crankcase 
and bearings and a third for the power cyl- 
inders. 

Lubrication 

Adequate and efficient lubrication is es- 
sential to the satisfactory operation, and free- 
dom from wear, of any machine or tool that 
has moving parts— and air tools and machines 
are no exception to this generality. 

There are three principal factors for good 
lubrication and they are as follows: 

1. The right kind and grade of lubricant. 

2. The effective application of the lubricant. 

3. Periodic attention from the operator. 

In other words, for good lubrication, care 
must be taken in choosing the right lubricant 
— oil, grease, or other product — for the re- 
quired service and condition of operation. In 
addition, dependable application of the lubri- 
cant must be insured through the provision 
of adequate lubricators, oil ducts and feed- 
ing mechanisms. 

Furthermore, periodic and systematic atten- 
tion must be paid to the lubrication system 
for even fully automatic arrangements may 
sometimes need attention. The supply of lubri- 
cants must be maintained; the rate of feed 
must be adjusted when necessary; and the 
lubricant must be kept free from contamination. 

Reputable oil refiners and other reliable 
suppliers of lubricants can furnish suitable 
products, kinds and grades for the required 
conditions. 

In specifying the lubrication requirements, 
the manufacturer of the equipment usually in- 
dicates the more important physical character- 
istics like viscosity, pour point, fire point, etc., 
and the minimum and maximum temperatures 
to be encountered, atmospheric conditions of 
operation, and the intended kind of service. 



261 



PLANT MAINTENANCE MANUAL 



Portable Type 

A reciprocating compressor of the portable 
type is a self-contained plant comprising "a 
compressor, prime mover and air receiver, 
complete with cooling, lubricating and starting 
systems, all enclosed by a canopy top and 
side doors and mounted on a unit chassis for 
ready movement." 

Maintenance 

Many of the suggestions already given for 
the proper operation and maintenance of sta- 
tionary systems also apply to portable units. 
Manufacturers supply detailed operating and 
maintenance instruction books, and these in- 
structions should be followed closely to ob- 
tain maximum successful performance of the 
equipment. 

Careful attention should be paid to the 
selection of the right size of hose or pipe in 
order that the pressure drop will be held 
within economical limits. Furthermore, a port- 
able compressor should never be towed at 
excessive speeds. 

Keep air receivers clean by draining them 
periodically. Fuel tanks and fuel strainers 
should also be kept clean. Check safety de- 
vices from time to time and replace ruptured 
strainers. 

The fuel used in the engine of a portable 
compressor should be of good quality and 
kept free from dirt. Although screens and fil- 
ters protect the engine from impurities, only 
clean fuel should be used. Clean filters once 
a week, and renew filtering elements -when 
necessary. 

In water-cooled units, use pure soft water 
if possible. Where good water is not avail- 
able, flush radiators and cylinder jackets 
every 300 hours. In extremely cold weather it 
is advisable to use an anti-freeze compound 
and it may also be necessary to cover the 
radiator partially to maintain a proper tem- 
perature of the cooling water. 

Selection of the proper lubricant is most 
important. Consult with reputable oil com- 
panies for their recommendations, giving them 
complete information regarding the require- 
ments and operating conditions. 

Inspect the entire unit completely after every 
300 hours of operation. Remove, inspect and 
clean the compressor valves. Also make any 
necessary bearing adjustments. 

Clean and repaint rust spots. Examine 
hinges and shut metal joints and repaint them 
as required. 



ROTARY COMPRESSORS, BLOWERS 
AND VACUUM PUMPS 

In rotary compressors, blowers and vac- 
uum pumps, the positive action of rotating ele- 
ments provides the compression. There are 
three general kinds of rotary machines: the 
sliding-vane type, the two-impeller positive 
type and the liquid-piston type. 

In general, the same precautions regarding 
the line valves and the general operation and 
care of reciprocating compressors apply also 
to rotary compressors and vacuum pumps. 

Foundation requirements of rotary machines 
however, are that the foundation should be 
substantial enough to support the unit and 
keep it in proper alignment. 

Study and follow the manufacturer's instruc- 
tions regarding correct operation and care 
of that company's machines. The maker's rec- 
ommendations as to lubrication should also 
be observed. No internal lubrication is re- 
quired in the two-impeller positive type blow- 
ers and vacuum pumps. 

CENTRIFUGAL AND AXIAL BLOWERS, 
COMPRESSORS AND EXHAUSTERS 

Centrifugal and axial blowers, compressors 
and exhausters are devices in which the dy- 
namic action of rotating vanes or impellers: 
compresses the air or gas by imparting velocity 
and pressure to the medium. Flow through a 
centrifugal machine is basically radial as dis- 
tinguished from that in an axial machine. 

Blowers or compressors in which the inlet 
pressure is less than atmospheric pressure and. 
the discharge pressure equal to, or greater 
than, atmospheric pressure are called ex- 
hausters. 

Lubrication 

In centrifugal and axial compressors the 
bearings are the only parts that require lubri- 
cation. Only the drivers of overhung units need 
lubricating since this type of machine has no 
bearings of its own. 

The bearings of pedestal and multi-stage 
machines require lubrication. Bearings of smail 
units may be of ball or roller types which need 
grease or oil lubrication or of the ring-oiled 
sleeve type which use a special grade of oil 
recommended by the manufacturer. 

Operation, Care and Maintenance 

Foundations of centrifugal and axial ma- 
chines should be substantial enough to sup- 
port the weight of the machine and rigid 
enough to hold alignment permanently. 

Efficient inlet air filters are advisable in 



262 



AIR COMPRESSOR EQUIPMENT 



dusty locations. Keep the inlet and discharge 
piping as short as possible. The former should 
be large enough to hold down friction loss 
and the latter should be of suitable size to 
keep frictional pressure drop to a reasonable 
limit. Be sure that the piping is clean. 

The lubricating system should also be free 
of foreign matter and kept filled with oil of 
the proper grade and composition. The en- 
tire lubrication system should be cleaned 
once a year. 

Bearings should be inspected at least once 
a year. It is usually good practice to over- 
haul the compressor at least once a year. At 
the same time inspect bearings and examine 
impellers for erosion and wear. 

ACCESSORIES 

Essential to every air compressor installa- 
tion, the air receiver is the storage reservoir 
that absorbs the pulsations of air from the 
compressor and insures a steady flow of air 
to the service line. In addition it acts as a 
reserve supply of air for sudden excessive 
demands and also as a precipitator for mois- 
ture in the air coming from the compressor. 
Pop safety valves are set slightly above the 
operating pressures. 

Water in compressed air is often the cause 
of annoyance and expense. It creates water 
hammer in pipe lines, reduces the capacity of 
the air lines and washes away the lubricant 
in pneumatic tools, the result being rapid 
wear and excessive air consumption which 
lead to high maintenance costs. The pres- 
ence of water has additional disadvantages. 

Some moisture is always present in com- 



pressed air, the degree depending upon the 
various operating conditions. The heated air 
leaving the compressor carries the moisture as 
vapor. Lubricating oil from the compression 
chambers also collects in the receiver and 
pipe lines unless removed. 

Water and oil vapor can be removed by 
condensing them. This is accomplished with 
the use of aftercoolers which cool the com- 
pressed air or gas, thus condensing the vapor 
for separation from the air. 

Filters should be employed to keep dust and 
other foreign matter out of the compressors 
and insure the entrance of clean air. They 
are placed on the air intake pipe. In the case 
of gas compressors, scrubbers are used. Filters 
should be of sufficient size regarding which 
point manufacturers will make suitable recom- 
mendations. 

Silencers are also available where noisy 
operation may be objectionable. 
Cleanliness 

Keep machines and equipment clean at all 
times, for cleanliness is a "must" of good 
maintenance. 

Dirty blades on flywheels and fins of afr 
cooled cylinders cause a machine to overheat. 
Dirt can also contaminate oil in the crankcase. 
Dirty air cleaners and intake mufflers will plug 
up and partially, or even totally, starve the 
compressor of air. 

In making repairs, cleanliness is also vital. 
Wipe off all parts carefully with a clean cloth. 
DO NOT use waste on internal parts. Never 
lay parts on the ground or on dirty benches. 

Specks of dirt, lint or thread in a bearing 
will cause it to burn out quickly. 



SYMPTOMS THAT INDICATE OPERATING DIFFICULTIES 


1. 


Oil pressure may be too low or too 
high, or oil delivery otherwise poor. 


2. 


Pressure cylinders may overheat. 


3. 


Incorrect intercooler pressures may be 
too high or too low, or intercooler 
vacuum may be low. 


4. 


Faulty control. 


5. 


Knocking and other noisy sounds. 


6. 


Scoring of piston and cylinder. 


7. 


Breakage of valves and springs. 


8. 


Failure to start or come up to speed. 



263 



PLANT MAINTENANCE MANUAL 



AIR OPERATED PORTABLE TOOLS 



Various Types of Pneumatic Tools 

ABRASIVE TOOLS -Die grinders, straight 
grinders, buffers, cone grinders, vertical grind- 
ers, sanders, wire brushing machines. 
AIR HOISTS, BALANCERS. 
COMPRESSION AND YOKE RIVETERS. 
DRILLS, REAMERS, TAPPERS, STUD SETTERS. 
PERCUSSION TOOLS - Chipping hammers, 
riveters, scaling hammers, sand rammers. 
SCREW DRIVERS, NUT SETTERS, WRENCHES 
AND IMPACT WRENCHES. 
SPECIALTY TOOLS - Air motors, concrete vi- 
brators, fender irons, ratchet wrenches, recip- 
rocating filing machines, rivet busters, saws, 
screw spike drivers, shears, staybolt riveters 
and tappers, sump pumps, tie tampers, valve 
grinders, weld flux scalers, woodborers. 

Pneumatic or air-operated portable tools 
are widespread in use because of their high 
power, light weight, compactness, flexibility 
and ease of control and operation. 

Three steps are necessary to obtain full 
advantage of pneumatic tools in cutting down 
production and maintenance costs. They are: 

1 . Select the correct tool for the job. 

2. Choose the correct accessories for the 
tool. 

3. Operate the tool at the proper speed. 

For maximum output with pneumatic tools 
be sure also that the supply of air is ample 
and that the proper pressure is delivered to 
the tool so that full power of the tool can be 
developed. 

The air pressure available at the tool may 
be determined by means of an air gage with 
a hypodermic needle attached. The needle is 
inserted into the air hose and the reading ob- 



served. The needle hole is self closing upon 
the withdrawal of the needle. 

If the pressure is inadequate, check the size 
of the main line pipes, down pipes, valves 
fittings and air hose. See the suggestions 
given elsewhere on "Low Air Pressure." 

For the exact secifications of pneumatic 
tools of the individual manufacturers, consult 
the company's catalogs. Seek the advice of 
the manufacturer in selecting the right tool for 
the job. 

Maintenance and Lubrication 

Production is maintained best when the tool 
efficiency is kept at 100 per cent. Where dust 
is present tools should be handled carefully 
to keep the dirt from being carried through 
the tool by the air. 

Only a few typical maintenance practices 
can be mentioned because of the great variety 
of tools available. 

One of the chief causes of wear with its 
resulting loss of power is the lack of lubrica- 
tion. Most portable tools have oil reservoirs. 
Fill them once or twice daily with a light oil, 
as recommended by the manufacturer. Tools 
that do not have an oil reservoir usually have 
an oiler in the air line. If not, inject oil in the 
air outlet every two or three hours. 

Water, which tends to wash off the lubricat- 
ing film , should be eliminated from air lines by 
the use of aftercoolers. 

When chippers and riveters, for instance, 
are taken out of service, they should be sub- 
merged in a bath of kerosene and light ma- 
chine oil. Before using them again, place a 
small amount of light machine oil in the air 
inlet and operate the tool for a few seconds. 
Furthermore, if chippers and riveters have 
been idle for a week or more, take them apart 




Determining Air Pressure Available 
by Air Gage with Needle Attachment 



264 



AIR COMPRESSOR EQUIPMENT 



and clean them. Then oil and reassemble them 
carefully. 

Adequate tachometers may be used for 
checking the governors that control the free 
speed of grinders and drills and thus keep 
them within the Safety Code. 

Wearing Parts 

Adequate and regular lubrication also in- 
creases the life of the blades or vanes of 
rotary type tools. When these parts become 
thin or badly worn, they should be replaced 
promptly. Follow the maker's instructions on 
this point. 

In the gear cases of portable tools, use the 
grade of lubricant or grease recommended 
by the manufacturer. 

Bearings also should be replaced when 
they show appreciable wear. If bearings are 
of the double-shielded type, merely wipe them 
clean, using care not to deform the shields. 



Manufacturers supply detailed instructions 
for the maintenance, care and repair of their 
tools. These instructions should be followed 
and applied for maximum working efficiency 
at a minimum of cost in operation. 

Supervising Maintenance 

The maintenance of portable air tools is 
relatively simple if the system is properly set 
up and supervised and if the work is per- 
formed by responsible, correctly-trained men. 
Manufacturer's service engineers will be found 
helpful in training these men. 

Even though manufacturers can usually make 
prompt shipments of repair parts, it is well to 
stock some of the parts that may be subject 
to wear. 

Regular checks should be made in order to 
avoid minor wear and serious breakdowns 
and resulting downtime. 




265 



PLANT MAINTENANCE MANUAL 









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267 



PLANT MAINTENANCE MANUAL 



LOW AIR PRESSURE 



The pressure and volume of air delivered 
to the point of use determine the air power 
available for work. If this pressure at the point 
where it enters the tool is inadequate, prac- 
tically all pneumatic tools will operate with 
lowered efficiency. 

For example, if a pneumatic tool is con- 
structed to operate at, say, 90 pounds gage 
maximum, the pressure within a range of 85 
to 90 pounds gage should be maintained. If 
the pressure drops below that range, the tool 
cannot perform at the maximum ability for 
which it was designed. In other words, main- 
taining air pressure at its proper value in- 
creases production and reduces the cost per 
unit produced. 

Operation of tools at "low air pressure," 
therefore, is a costly and wasteful abuse of 
equipment. 

Causes of Low Pressure 

low pressure results from insufficient com- 
pressor capacity, inadequate piping and leak- 
age. 

When the air pressure is found to be too 
low, the most common procedure would be to 
install more compressor capacity. This step, 
however, should not be taken until it is de- 
termined that the air pressure is low when the 
compressor is at full load. If such is the fault, 
more capacity may be needed. But even then, 
it is best to investigate the other two causes 
also. 

Inadequate Piping 

Inadequacy of the piping may be measured 
by ascertaining the pressure loss between the 
receiver and the point of use. If the system is 
well designed, the loss should not exceed 
10% and the maximum absolute drop for the 



worst point should not be more than 15%. If 
the pressure drops are greater than those 
values, the distribution system should be cor- 
rected before increasing compressor capacity. 

Leakage 

loss of air through leakage is a wastage 
of work power that has no justification. No 
operator of a compressor would think of 
exhausting it direct to the air, yet that is just 
what an excessive leak does. 

Eliminating leaks, then, is essential to main- 
taining air pressure and conserving power be- 
cause it puts back to daily useful work oir 
that was formerly wasted. Making lines air 
tight is far less costly than the installation of 
a new compressor. 

Any loss of "more than one cubic foot per 
minute per mile of 3-inch line" is regarded as 
excessive by the gas industry. 

While most air leaks are usually quite 
small, a number of small leaks can lose a lot 
of air. For instance, one j'^ inch hole can 
waste 182,000 cubic feet of air per month. 
Remedies 

Poor planning, or the increased use of air 
without expanding the system, is usually re- 
sponsible for faulty conditions of air power. 

The matter of pipe size is also a factor since 
pressure loss varies approximately with "the 
square of the velocity of air flow through the 
pipe." A 3-inch line, 1000 feet long, for ex- 
ample, will handie about 500 cubic feet per 
minute with a pressure loss of 2 ] /2 pounds,- a 
4-inch line, however, will handle about 1000 
cubic feet per minute with the same drop. The 
labor charges, the largest item in laying pipe, 
for installing a 4-inch pipe are little more than 
for a 3-inch pipe. 



LOW PRESSURE IS 
A COSTLY AND 
WASTEFUL ABUSE 



PROPER PRESSURE 
INCREASES PRODUCTION 
AT LOW COST. 




268 



AIR COMPRESSOR EQUIPMENT 



Increasing pipe line capacities to improve 
pressure conditions may be accomplished by 
several means. A new line may be run par- 
allel to the original with frequent connections 
between the two. Or a loop system with out- 
lets off the new line may correct the trouble. 
A third method is a complete new system. 

Over-sized branch lines and manifolds 
should be used for tool attachments. 

It is also important to pay attention to the 
size of the hose that carries the air to the 
tool. Losses up to 25% in air pressure have 



occurred in bad hose lines. The hose line, 
however, should not be larger than necessary 
for the freedom of movement and for reaching 
the work. 

Regular inspections of every section in the 
hose line should be made for leaks. Examine 
carefully such locations as those around valve 
stems, hose connections, unions, drains, home- 
made blow guns and lines to inoperative tools. 

Compressor capacity should be increased 
only after leaks have been eliminated and the 
distribution system found inadequate. 



269 



m 


Ul 




Ifc^w 




' -' 'ib"^*^^^^^ 



CHAPTER 25 



HEATING EQUIPMENT 



Industrial heating systems are usually con- 
sidered according to the heating medium or 
the kind of equipment used, such as steam, 
hot water, vacuum, vapor and vacuum, unit 
heaters, etc. 

In many modern plants, heating is one of 
the functions of the air conditioning system. 
Air conditioning, in the broader sense of the 
word, however, also includes ventilating, cool- 
ing, humidifying or dehumidifying, and air 
cleaning. This chapter will, therefore, limit it- 
self to strictly heating equipment and will give 
emphasis to heating devices rather than to 
the power plant phases. 

Maintenance of heating systems comprises 
periodic inspections of piping systems, radi- 
ators, heating coils, unit heaters, valves and 
traps. Some of these items, traps, for instance, 
have been covered in Chapter 22. The main- 
tenance of valves was considered in Chapter 
21. 

Necessary repairs should, of course, always 
be made. If they are of a minor nature, it is 
usually possible to make them as needed. If of 
a large nature, however, they may often be 
postponed until summer time when the entire 
system can be checked and overhauled to 
make it ready for the following winter. 



According to the American Society of Heat- 
ing and Ventilating Engineers, winter inside 
dry bulb temperatures commonly specified for 
factories and machine shops are 60 to 65 deg. 
F. The "most comfortable dry bulb tempera- 
ture" depends, of course, on "the relative 
humidity and air motion." 

HEATING POWER PLANT 

A common form of heating industrial plants 
is by the use of steam because many a man- 
ufacturing enterprise generates its own power 
or steam which it uses in its processing opera- 
tions. In such cases it is customary to reduce 
the steam which is taken from the high pres- 
sure power plant to the lower pressure re- 
quired by the heating system. Sometimes ex- 
haust steam from engines or turbines is used. 

Recently in many large industrial buildings, 
however, heating systems have been designed 
for high pressure steam. These installations, 
which are without pressure-reducing valves, 
commonly employ unit heater distribution or 
use large fan units which have blast heating 
coils. 

If, however, power is purchased, it is nec- 
essary to install equipment to supply the re- 
quired pressure steam. 



270 



HEATING EQUIPMENT 



■ IIIEF V4LVIS 




Cut-away of a Boiler Arrangement 



With adequate equipment which is intel- 
ligently operated by well-trained and experi- 
enced men, sudden breakdowns in power 
plant apparatus are few and far between. 
In this respect, then, it is difficult to draw the 
exact line at which operation ends and main- 
tenance begins. Wear, however, cannot be 
prevented. So to combat wear, regular in- 
spections, adjustments, lubrication, cleaning 
and minor repairs are needed in every plant. 

The objective of a good maintenance pro- 
gram, then, is to assure continuous efficiency 
of operations. Four good rules to observe 
are as follows: 

1. Schedule maintenance inspections as a 
routine part of plant operations. 

2. Establish definite periods for servicing 
every unit of equipment. 

3. Follow the servicing recommendations of 
the manufacturers of the equipment in- 
stalled. 

4. Watch boiler operations closely. 



General Maintenance 

Be sure to follow the manufacturers' instruc- 
tions for the operation and care of their 
equipment since the detailed procedures may 
vary with the make of the apparatus. Some 
general suggestions, however, may be offered. 

Cleonouts— From the point of view of up- 
keep of furnace cleanouts and chimney two 
main considerations are protection from cor- 
rosion and the maintenance of a tight seal 
when cleanouts are shut. Therefore, clean the 



cleanout doors thoroughly when the furnace is 
shut down. Keep the doors painted with a cor- 
rosion inhibiting coating for use on metal 
under highly corrosive conditions. Lubricate 
the hinges and locking levers of cleanouts oc- 
casionally to facilitate their operation. 

Dampers, Regulators — Keep the bars and 
connections of hand-operated regulators clean 
and lubricate moving parts sufficiently to oper- 
ate easily. Check and inspect automatic regu- 
lators about every three months to make sure 
that gaskets, diaphragms and packings are 
not unduly worn and that weights, chains, bal- 
ance bar, etc., are clean and free from cor- 
rosion. 

Check steam and water connections often. 
Clean- water chamber from possible sediment. 

Grates— Grate damage and need for re- 
pair are lessened by expert boiler firing. Main- 
tenance, therefore, is closely related to fur- 
nace operation. If the draft is improperly 
regulated or if the plant is subject to con- 
stant overloads, sections of the grates may 
burn out, or otherwise be damaged. Preven- 
tion of damage to grates, therefore, involves 
making sure that the stoker mechanisms are 
in good repair and operate properly at all 
times. 

Gages— Good boiler room practice dic- 
tates constant maintenance of all types of 
gages. Gage glasses should be inspected 
frequently for possible leakage. Tubular 
glasses should be changed regularly, de- 
pending upon the type and operating con- 
ditions, before dangerous thinning. 



271 



PLANT MAINTENANCE MANUAL 



Check gage ports daily for freedom from 
sediment by opening blowdown valve. Make 
sure that packing around valve stem and gage 
glass is tight. Check clamping bolts on gage 
glass inserts for pressure, and take up as 
necessary to prevent gasket blowouts and 
minimize glass erosion. 

Relief Valves— Relief valves should receive 
as frequent attention as any other part of 
the steam boiler heating plant. Inspect, clean 
and service as often as the boiler is shut 
down. If valves start to leak repair them at the 
first possible opportunity because constant 
leaking tends to erode and damage valve 
seats. 

Lubricate valve stem as often as necessary 
to assure free movement. Renew stuffing box 
packing before it becomes hard. Lap in the 
manner and with the tools recommended by 
the valve manufacturer, and be careful not 
to lap too much as that merely wears away 
the seat without improving operation. 

When reinstalling, tighten all bolts evenly 
to avoid strain on the valve body. If connec- 
tions are screwed, use wrench on the valve 
side of the pipe joint. Test with clean air or 
dry steam, if possible, in order to keep from 
getting dirt or grease under the seat. 

If discharge pipe is used, be sure it is the 
same size as the inlet so as to avoid the 
creation of back pressure. Discharge piping 
should be supported so that no strain is im- 
posed upon the valve itself. 

Boiler Tubes 

Efficient and economical steam heating 
plant operations depend to a large extent 



upon keeping boilers as nearly as possible in 
their original condition. It is good practice 
to shut down a boiler every three to four 
months, in some cases, for cleaning and a 
complete checkover. Where operations are 
light, however, this period may be extended 
considerably. 

Scale and other matter detrimental to good 
boiler performance may form to sorrm extent 
in most every boiler and must be removed 
periodically. Boiler tubes should also be 
cleaned inside and out. Inside cleaning may 
be accomplished by a scraper and a brush on 
a universal coupling or by the use of me- 
chanical scale-cutting heads driven by water, 
steam or compressed air. Cleaning of these 
mechanical devices after use is important. 
They should be stored carefully and in the 
manner recommended by the maker. 

Keep boiler surfaces clean. Exterior ac- 
cumulations on all tubes and drum surfaces 
should be scraped thoroughly and brushed. 
Steam, air or hot water can usually help to 
remove encrusted soot and other deposits 
of dirt. 

Be certain that the coal, if used, is the 
right grade for the boiler, or that the oil is 
clean and properly conditioned for efficient 
burning. 

Other items of heating plant equipment 
that require periodic attention are boiler feed 
apparatus, steam pumps, compressors, blow- 
ers, coal stokers and pulverizers, oil burners 
and gas burners. Manufacturers of these 
pieces of equipment can readily supply com- 
plete information on the proper maintenance 
of their products. 




272 



HEATING EQUIPMENT 



A Dozen General Guides to Maintenance 



1. Service space heating equipment in all 
plant areas, including offices, at beginning 
and ending of heating season and check over 
for adjustments and minor repairs at least 
once a year, before it is put into service. 

2. Check piping system for proper align- 
ment, adequate pitch in all mains and 
branches, condition of pipe insulation, leaks 
at connections, valves, traps, etc., and ade- 
quate air vents, cleanouts, strainers, etc. 

3. Inspect all heat supply equipment— boil- 
ers of any type, boiler feed apparatus, heat 
exchangers, pumps, motors, controls, etc. 
Drain, clean and repair in spring,- inspect and 
adjust in fall. 

4. In the spring clean boilers or heat- 
exchanger tubes of scale and sediment, flush 
thoroughly and leave open to permit air cir- 
culation during disuse period. Inspect seals, 
gaskets, etc., and repair broken coverings. 

5. Drain, clean and flush receiving tanks 
and leave open if possible for air circulation. 
Inspect exterior for corrosion spots and re- 
paint with rust-inhibiting formula of proved 
quality. 

6. Open, clean and oil boiler return traps, 
drip traps, radiator traps, and air vents. Check 
adjustments of trap and air vents; and check 
leaking radiator and gate valves for worn 
packings and gaskets. 

7. Good practice is to remove electric 
motors from pumps, compressors, etc. Clean, 
oil and repair them as needed. Cover and 
store in a dry place to prevent condensation 
that may form on and damage windings. 

8. Inspect, clean, oil and adjust switch 
mechanisms on motor starters, float and 
vacuum switches to overcome severe arcing 
that may result from stiffness caused by lack 
of servicing. Check condition of wiring. 

9. In steam systems inspect radiators, heat- 
ing coils of all types, unit heaters, etc., for 
water pockets in riser and unit runouts that 
tend to prevent adequate supply of steam 
or proper condensate return. 

10. Such pockets may be caused by in- 
sufficient pitch, inadequate venting, improper 
trapping. Check system for these points to 
avoid hammering, loss of efficiency and pos- 
sible damage to valves and traps. 

11. Check system for both adequacy and 
condition of all thermostatic control elements 
as valves, flow regulators. Operate at best 
pressures,- excessive pressures tend to shorten 
life of elements. 



12. In air-operated temperature control sys- 
tems, check connections between compressor, 
air storage tank and pipe lines to eliminate 
leaks. Keep thermostats clean of dust that 
may prevent proper functioning. 




273 



PLANT MAINTENANCE MANUAL 



UNIT 

For space heating, the use of unit heaters 
has become increasingly popular. Unit heat- 
ers are so called because they are enclosed, 
factory-made assemblies of apparatus de- 
signed for the purpose of heating. They con- 
sist essentially of a fan and motor, the heat- 
ing elements or arrangements, the housing, 
and diffusers or outlet vanes for the distribu- 
tion of the heated air. 

Unit ventilators are somewhat similar as- 
semblies whose purpose is to ventilate by 
circulating air within a fixed area, or to in- 
troduce air from the outside. Sometimes both 
functions are accomplished. 

The heating function of unit heaters may 
be accomplished by steam or hot water; by 
electricity; or by gas, oil or coal fired ar- 
rangements. 

Fans are of the propeller type or of the 
centrifugal type. In either case, they may be 
designed for horizontal or vertical installa- 
tions according to whether the unit is for 
horizontal or vertical delivery of air. Fans 
may also be arranged to draw the air through 
the heater elements or blow it through them. 

Unit heaters are commonly used because 
they possess the features of rapid heating, 
directed heat, ease of control, simple piping 
arrangements. It is also unnecessary to keep 
heavily banked fires over-night. 

Unit heaters are of two general types, over- 
head and floor. Support of the suspended 



HEATERS 

types may be accomplished by the piping or 
independent supports. The larger kinds of 
space heaters are usually located on the 
floors with the discharge high enough to 
avoid blowing directly on the working level. 

In one steam type of overhead unit heaters, 
for instance, air is drawn from the room area 
and is blown by fans over the heater unit coils, 
which are connected to the steam supply line, 
and out into the room. The heated air stream 
is diffused and directed downward toward 
working levels. Fresh air may be introduced 
where necessary. Automatic temperature 
control by means of thermostats and switches 
is possible and humidifying and filtering 
equipment are also available. Volume of air 
may be regulated. Uniform heat distribution is 
possible by spotting the heaters at suitable 
locations throughout the building area. 

In addition to space heating, unit heaters 
are also used in industrial processing where 
the rapid circulation and uniform distribution 
of heated air is advantageous, as in drying 
and curing. They may also be used to absorb 
moisture and prevent condensation on ceil- 
ings, walls and other cold surfaces of build- 
ings where moisture laden air is present. 

Unit heaters may also be used in summer 
time to circulate air and provide air-motion 
comfort. In such cases, of course, the unit 
should be controlled so that the fan operates 
independently of the heating elements. 




Unit Heaters 




274 



HEATING EQUIPMENT 




Proper Installation 
Reduces Maintenance 

In unit heater installations, three points 
should be considered: location of the unit, 
air distribution and heating medium. 

The "throw" for which unit heaters are 
designed is important and should not be ex- 
ceeded. Throw may vary from 20 feet to 200 
feet. Outlet velocities range from 400 to 
25,000 feet per minute, depending upon the 
type of unit and the air throw requirements. 
Directional outlets, diffusers or louvres direct 
and diffuse the heated air as desired. 

Unit heater are customarily rated accord- 
ing to the amount of heated air delivered in 
Btu's per hour. These heat units are values 
above an entering temperature of 60 deg F. 
Other factors are, of course, used in making 
comparisons between types of heaters. 

Steam Type Unit Heaters 

Rating codes standardized by the American 
Society of Heating and Ventilating Engineers 
and the Industrial Unit Heater Association 
apply to steam type units. They are based 
upon a dry saturated steam pressure of 2 
psig at heater coil and an entering air tem- 
perature as specified above. The heater is 
also considered as operating without external 
resistance to the flow of air. Heating capaci- 
ties at other steam pressures and entering 



air temperatures than those mentioned above 
are arrived at by the use of specially pre- 
pared conversion factors. Manufacturers of 
steam unit heaters can supply these data and 
often have prepared special tables giving 
these calculated values. 

Hot Water Type Unit Heaters 

Standard rating codes for hot water type 
heaters have been established by the Indus- 
trial Unit Heater Association. These ratings 
are based on entering hot water at a given 
standard or average temperature, and the 
same entering air temperature, and without 
external resistance to air flow, as in the case 
of steam units. 

Manufacturers also provide correction fac- 
tors for use in calculating capacities for 
operation at various other water tempera- 
tures, air temperatures and water tempera- 
ture drops. 

When installing hot water heaters, it is 
advisable to size, connect and arrange the 
piping so that an adequate amount of water 
will flow to each unit heater. Locate air 
valves or reliefs for the rapid and complete 
removal of air. When shut downs in cold 
weather occur, the system should be drained 
to prevent freezing. Proper installation of the 
piping is necessary for this last named pur- 
pose. 



275 



PLANT MAINTENANCE MANUAL 




Electric Unit Heaters 

Rating of electric unit heaters is based on 
the amount of energy input in terms of kw, 
Btu or EDR (Equivalent in Direct Radiation). 
These three related classifications are often 
listed together. 

Electric heaters have heating elements of 
the resistance type and a fan and motor in a 
suitable housing. The motor-driven fan cir- 
culates room air over the heating elements. 
These unit heaters are available in portable, 
suspension or built-in-wa|l type. 

These heaters are advantageous where in- 
dustrial power rates for heating are eco- 
nomical and may be used to advantage in 
large areas and in small scattered locations. 
Portable units are extremely applicable for 
temporary installations in many different kinds 
of places. 

Automatic thermostatic controls may be 
obtained in order to hold temperatures to 
given limits. Sizes of electric unit heaters go 
up to 60 kw or 204,900 Btu or 854 square feet 
in EDR at least in capacity. 

Direct Fired Types 

Gas fired types of unit heaters have either 
propeller or centrifugal style fans. Sizes run 
from 45,000 to 1,650,000 Btu. Models are 
either suspended or floor types. The American 
Standards Association has set up approval 



requirements of gas-fired units in both out- 
put and input ratings. 

The output capacities of oil-fired unit heat- 
ers range from 125,000 to 1,650,000 Btu per 
hour. Both floor mounted and suspension 
types are used. Fans may be of the propeller 
or centrifugal kinds. 

In the case of coalfired heaters, capacities 
range from 300,000 to 6,000,000, and over, 
Btu delivered per hour. 

Location of Unit Heaters 

Unit heaters should be located so that the 
circulation of air is not impeded. There should 
be a minimum of interference from machinery, 
columns and partitions. Horizontal units should 
be arranged so as to produce a rotational 
circulation around the area to be heated. 
One way to accomplish this circulation is to 
set the heaters parallel to the exterior walls 
and near, but not in, corners in such a way 
that they support each other and provide even 
heat distribution. A uniform, geometric ar- 
rangement also simplifies the piping and other 
installation costs. 

When vertical units are used, they should 
be arranged to overlap a bit in coverage and 
so to blanket exposed walls. 

Combined applications of both horizontal 
and vertical units are advantageous in cer- 
tain instances— with vertical units in high-ceil- 



276 



HEATING EQUIPMENT 




ing areas and horizontal units in low ceiling 
sections. 

Horizontal units, sometimes of a high- 
velocity type, are used in front of large door- 
ways with the discharge directed against the 
open doors to keep out the cold air. 

To keep hot air blasts from being objec- 
tionable, the discharge outlets of floor type 
units should be directed above the working 
zone. The outlets, however, should bring the 
heated air as close as possible above the 
head line. 

Attention, too, should be paid to proper 
mounting heights for unit heaters and for their 
heat throw. Different arrangements are sup- 
plied for a wide range of mounting heights 
of vertical heaters. 

The manufacturers of unit heaters can sup- 
ply valuable help on the effective location of 
their equipment. 

Piping Arrangements and Connections 

For the sake of giving more specific infor- 
mation, procedures for a representative steam 
unit heater installation will be presented, since 
space will not permit giving complete details 
on all types. 

The piping system distributes the steam to 
the unit heaters and returns the condensate 
to the boiler. The line to the unit heater must 
be of adequate size to handle the steam. The 
return pipe must be of appropriate size to 
provide adequate drainage for the elimina- 
tion or carrying-off of the condensate. Since 
the condensation rate varies rapidly, this pre- 



caution is a very important one to observe. 

Proper piping arrangements depend, of 
course, on the heating system used— whether 
it is one pipe gravity, vacuum or vapor, high 
pressure steam, or a hot water system. Manu- 
facturers will gladly recommend the proper 
piping and connections for their equipment. 

Steam traps should be of sufficient capacity 
to take care of the condensate under maxi- 
mum operating conditions. In fact, the traps 
installed should be such that they provide a 
reasonable safety factor in capacity. Here 
again, it is well to consult with steam trap 
makers regarding capacities of their devices. 
Boiler Capacity 

Make sure that boilers used for steam unit 
heaters are not only sufficient for "rated ca- 
pacity of the unit heater at the lowest enter- 
ing air temperature and highest possible fan 
speed" but also to take care of pipe line 
losses. 

Inspections should be made for the pos- 
sibility of corrosion in the steam system since 
entrapped air can cause corrosion. Attention 
should be paid to the condition of the boiler 
feed water. Advice on matters of Ihe proper 
treatment of feed water may be obtained 
from specialists in that field. 

Electric Wiring 

In many unit heaters motors perform es- 
sential functions, so consideration should be 
given to the electrical equipment. 

Check also the protective and the control 
devices, wiring and accessory apparatus. 
Among the electrical devices and equipment, 



277 



PLANT MAINTENANCE MANUAL 




in addition to the motors, are the following: 
disconnect switches, fuses, manual and mag- 
netic starters, relays, selector switches, limit 
control. 

Considerable information on the mainte- 
nance of these items will be found in another 
chapter, namely No. 6, on Industrial Controls. 

UNIT HEATER MAINTENANCE 

Maintenance practices governing unit heat- 
ers naturally vary according to the kind, and 
manufacturers of heater equipment can offer 
valuable aid regarding the best maintenance 
practices for their apparatus. Such instructions 
should be followed carefully. 

To provide a concrete example, however, 
the procedures for one representative type of 
steam unit heaters will be considered in some 
detail as follows. 

Regular Inspections 

These unit heaters should be inspected 
regularly— onc'e every four months for equip- 
ment operating under average conditions. If 
unit heaters are located in places where the 
air is dusty or sooty, or where corrosive fumes 
or oil sprays are present, the equipment 
should be inspected more often. 

In these inspections look for dirty and 
clogged condensers, loose connections and 
excessive vibration. 

Check motors and fans for proper opera- 
tion and cleanliness. Remove dirt and grease 
from the outside of the motors. It is usually 



good practice to dismantle the motors every 
three years or so and clean them thoroughly. 

Motors should also be lubricated properly 
as required from the inspection. If bearings 
are of the sleeve type, make sure that oil cups 
are kept filled. Oil with a light engine oil once 
or twice a year. Some bearings require very 
little oil, so be sure not to overlubricate. 
Chapter 12 which covers sleeve bearings will 
give current practices with regard to these 
kinds of bearings. 

Inspect shafts for end play—and replace 
thrust washers if too much play. 

Bearings of the anti-friction type usually 
contain lubricant for at least a year's opera- 
tion. It is usually good practice, however, to 
repack bearings after some 2,000 hours of 
operation. Use care in applying grease with 
a grease power gun so as not to force lu- 
bricant into the armatures. Be sure not to 
over-lubricate. Examine bearings for worn 
parts. See Chapter 1 3 on the Ball and roller 
Bearings 

Note plant voltage conditions for the effect 
on motors, since wide variations in voltage, 
either up or down, can overheat a motor 
causing serious damage. One well-known 
manufacturer recommends "a separate manual 
starter with thermal overload protection de- 
vice for each unit." 

Recommended practices for the care and 
maintenance of electric motors are given in 
Chapter 3. 



278 



HEATING EQUIPMENT 




Condensers or Heating Coils 

Dirt can seriously reduce heating capacity. 
To maintain maximum heating capacity, keep 
the condensers or other heating elements 
free of dirt or grease and other foreign par- 
ticles that may be present in the air or come 
from manufacturing processes. 

Under ordinary circumstances, therefore, 
condensers should be cleaned at least once a 
year. If operating conditions are poor, clean 
more often. Where corrosive fumes are pres- 
ent, the condensers should be examined and 
cleaned more frequently. 

Cleaning may be accomplished in several 



ways. One method makes use of the fan ac- 
tion of the heater itself. Dirt is loosened by 
brushing the air-entering side and blowing 
out the dirt by turning on the fan. Another 
plan is to loosen and blow out the dirt with 
a high pressure air hose or with portable 
blowers. 

If a more thorough cleaning is called for, 
one maker of unit heaters suggests the re- 
moval of the motor and the spraying of the 
condenser with a mild alkaline cleaning solu- 
tion. Then after some minutes, rinse with hot 
water. Both spraying and rinsing may be ac- 
complished with a steam gun. 




279 



PLANT MAINTENANCE MANUAL 



Boiler Feed Water 

Treat boiler feed water with the proper 
boiler compound, as suggested by the manu- 
facturer. But be careful not to use too much 
compound, or an unsuitable one. This practice 
helps to prevent corrosion. De-aeration of 
boiler feed water has also been recom- 
mended. 

Condensate Drainage 

Proper operation of traps is important be- 
cause their failure to work satisfactorily will 
cause condensate to accumulate in the heater 
coils with the possibility of damage from a 
water hammer. 

Check traps for adequate capacity to 
handle the condensate requirements and for 



proper installation. Examine them for sticking 
mechanisms and other troubles. 

Check also the strainers, which are placed 
ahead of the traps. Keep the strainers clean. 

See Chapter 22 on Traps and Strainers 
for trap troubles and their cures. 

Housings or Casings 

Clean unit heater housings periodically, re- 
moving dirt, grease and other injurious foreign 
matter. Wherever rust or corrosion is found, 
clean the spot and repaint for protection. 

Fan guards and motor brackets should be 
tight. 

Check fans from time to time for proper 
clearance and good rotation. Fans should be 
connected firmly to shafts. 



280 




CHAPTER 26 



AIR CONDITIONING EQUIPMENT 



Maintaining the atmosphere to a required 
temperature, humidity and purity in an in- 
dustrial plant is most important to many manu- 
facturing processes. In some industries it is 
vitally necessary. For the presence of moisture, 
heat, cold, dust, fumes and other harmful 
conditions can seriously affect many products. 

Industrial air conditioning then offers the 
following features as an aid to production-. 

a. Provides close temperature control for 
maintaining dimensional accuracy of ma- 
terials being machined and of the gages 
and other apparatus being used for check- 
ing those dimensions. 

b. Reduces high spoilage and rejections of 
products where unusual temperatures and 
humidities cause sweating and corrosion. 

c. Prevents dirt and dust spoilage in assem- 
blies of fine mechanisms. 

d. Controls moisture content and regain in 
the storage of, and in other operations in- 
volving, hygroscopic materials— those that 
absorb moisture from the air. 

e. Supplies reasonable worker comfort for 
improved mental and physical being and 
helps to increase individual productivity. 

Temperatures and Humidities 

The product and the nature of an operation 
on it determine the relative humidity and the 
temperature most favorable for a processing 
or handling requirement. Thus each material 



and process, and even different processes in 
the manufacture of the same material or prod- 
uct, may have different air conditioning re- 
quirements. Some of these varying require- 
ments are shown in the table listing the 
temperatures and humidities applicable to in- 
dustrial air conditioning. 

In some of the industrial applications listed; 
reasonable worker comfort and efficiency are 
more important influences than are the prod- 
uct or process. So when industrial materials 
and processes call for atmospheric conditions 
that may be detrimental to human comfort, a 
reasonable compromise is highly desirable. 

AIR CONDITIONING TERMS 

AIR CONDITIONING -The simultaneous 
control of all or at least the first three of 
those factors affecting both the physical and 
chemical conditions of the atmosphere within 
any structure. These factors include tempera- 
lure, humidity, motion, distribution, dust, bac- 
teria, odors and toxic gases, most of which 
affect in greater or lesser degree human 
health or comfort. 

COMFORT AIR CONDITIONING -The 
process by which simultaneously the tempera- 
ture, moisture content, movement and quality 
of the air in enclosed spaces intended for 
human occupancy may be maintained within 
required limits. 

ABSORPTION-The action of a material in 



281 



PLANT MAINTENANCE MANUAL 



extracting one or more substances present in 
an atmosphere or mixture of gases or liquids; 
accompanied by physical change, chemical 
change, or both, of the sorbent. 

ADSORPTION-The action, associated with 
surface adherence, of material in extracting 
one or more substances present in an atmos- 
phere or mixture of gases and liquids unac- 
companied by physical or chemical change. 
Commercial adsorbent materials have enor- 
mous internal surfaces. 

COMFORT ZONE (Average)-The range 
of effective temperatures over which the ma- 
jority (50 per cent or more) of adults feel 
comfortable. 

DEHUMIDIFY— To reduce, by any process, 
the quantity of water vapor within a given 
space. 

DEHYDRATE— To remove water in all forms 
from matter. Liquid water, hygroscopic water, 
and water of crystallization or water of hy- 
dration are included. 

HUMIDIFY— To increase, by any process, 
the density of water vapor within a given 
space. 

HUMIDITY, RELATIVE-The ratio of the 
actual partial pressure of the water vapor 
in a space to the saturation pressure of pure 
water at the same temperature. 

REFRIGERANT-A substance which pro- 
duces a refrigerating effect by its absorption 
of heat while expanding or vaporizing. 

VENTILATION— The process of supplying 
or removing air, by natural or mechanical 
means, to or from any space. Such air may or 
may not have been conditioned. 

FUNCTIONAL CLASSIFICATION 
OF SYSTEMS 

One basic method of classifying air condi- 
tioning equipment is according to its function. 
These functional classes, according to the 
Heating, Ventilating, Air Conditioning Guide 
of ASHVE, are as follows: 

WINTER AIR CONDITIONING-The func- 
tion is to ventilate, heat and humidify in winter 
the spaces under consideration, and provide 
the desired degree of air motion and air 
cleanliness. The equipment required normally 
consists of a preheater, filters, humidifying 
sprays or air washer, reheater, fan, distribut- 
ing ducts, and the necessary manual or auto- 
matic means of control. 

SUMMER AIR CONDITIONING-The func- 
tion is to ventilate, cool and dehumidify the 
spaces under consideration and to provide 
the desired degree of air motion and cleanli- 
ness. The normal complement of equipment 



includes filters, dehumidifier with its source of 
cooling, reheaters or by-pass if required, fan, 
distributing ducts, and the necessary manual 
or automatic means of control. 

YEAR 'ROUND AIR CONDITIONING-The 
function is to ventilate, heat and humidify in 
winter and cool and dehumidify in summer the 
spaces under consideration, and to provide 
the desired degree of air motion and cleanli- 
ness. The equipment usually comprises pre- 
heater, filters, spray or surface dehumidifier, 
reheaters and by-pass if required, fan, system 
of distributing ducts, and necessary means of 
manual or automatic control. 

Some of the pieces of equipment in these 
groups may be replaced with others which 
serve the same purpose, such as the replace- 
ment of a dehumidifier by an absorption type 
dehydrator with after cooler. 

Also a certain kind of system can be modi- 
fied or changed by omitting some functions 
and including others, such as the conversion 
of a winter air conditioning system to a simple 
warm air heating system or even to a simple 
ventilating system by omitting certain func- 
tional apparatus. 

Operation and Care 

The best source of information on the op- 
eration, care and maintenance of air condi- 
tioning equipment is the manufacturer of the 
apparatus used. Consideration of this fact is 
particularly important because different tech- 
niques are usually required to repair and 
maintain the various makes of equipment. 
Furthermore, refrigerating systems are inher- 
ently complicated, and knowledge of the 
theory of refrigeration is essential in perform- 
ing any service on it. 

What the maintenance department of on 
industrial plant should do is to inspect the 
apparatus and perform certain checks and 
diagnose troubles. Then call in an air condi- 
tioning service engineer, especially when over- 
hauling any equipment. 

Only some of the more general mainte- 
nance procedures will be presented in this 
chapter as it is not possible, obviously, to give 
complete details on all the many kinds of 
equipment. 



Note: This table is reprinted from the Heating Venti- 
lating Air Conditioning Guide 1947, which is also the 
source of the terminology and the table of equipment 
based on load factors appearing in this chapter. 

This Guide, published by the American Society of 
Heating and Ventilating Engineers, contains much 
valuable data on air conditioning equipment. Always 
use the latest edition. 



282 



AIR CONDITIONING EQUIPMENT 



TEMPERATURES AND HUMIDITIES APPLICABLE 
TO INDUSTRIAL AIR CONDITIONING 



INDUSTRY 



AUTOMOBILE 



PROCESS 



TEMPERATURE RELATIVE 

FAHRENHEIT HUMIDITY 

DEGREES PER CENT 



CHEMICAL ■ 



ELECTRICAL 



INSTRUMENTS 



LABORATORY 



MUNITIONS — 



PRINTING 



Assembly line 65 to 80 40 to 55. 

Precision parts— honing— machining ... 75 to 80 40 to 55 

Drying of auger machine brick 1 80 to 200 

Drying of refractory shapes 1 10 to 150 50 to 60 

Molding room 80 60 

Storage of clay 60 to 80 35 to 65 

General storage 60 to 80 35 to 50 

Insulation winding 104 5 

Manufacture of cotton covered wire .... 60 to 80 60 to 70 

Manufacture of electrical windings .... 60 to 80 35 to 50 

Storage of electrical goods 60 to 80 35 to 50 

Repair and calibration 68 50 to 55 

General analytical and physical 60 to 70 60 to 70 

Storage of materials 60 to 70 35 to 50 

Drying of hides 90 

Mulling 95 to 100 95 

Manufacturing 72 to 74 50 

Storage of matches 60 

Fuse loading 70 55 

Air drying lacquers 70 to 90 25 to 50 

Baking lacquers 180 to 300 

Air drying of oil paints 60 to 90 25 to 50 

Binding, cutting, drying, folding, gluing 60 to 80 40 to 60 

Storage of paper 75 to 80 40 to 60 

Testing Laboratory 60 to 80 55 to 65 

Binding 70 45 

Folding 77 65 

Press room (general) 75 60 to 78 

Press room (lithographic) 75 to 80 50 to 60 

Storage of rollers 70 to 90 50 to 55 

Manufacturing 90 

Dipping of surgical rubber articles 75 to 80 25 to 30 

Standard laboratory tests 80 to 84 42 to 48 

Cementing 80 25 to 30 

Cotton — carding 75 to 80 50 to 55 

combing 75 to 80 60 to 65 

roving 75 to 80 50 to 60 

spinning 60 to 80 50 to 70 

weaving 68 to 75 85 

Rayon — spinning 70 85 

throwing 70 60 

weaving 75 to 88 60 to 75 

Silk — dressing 75 to 80 60 to 65 

spinning 75 to 80 65 to 70 

throwing 75 to 80 65 to 70 

weaving 75 to 80 60 to 70 

Wool - carding 75 to 80 65 to 70 

spinning 75 to 80 55 to 60 

weaving 75 to 80 50 to 55 

Testing Laboratory 70 65 



283 



PLANT MAINTENANCE MANUAL 




BASIC CLASSIFICATIONS 

One other classification of air conditioning 
systems is according to the method of fabri- 
cation—central and unitary. 

A central system is defined by the American 
Society of Heating and Ventilating Engineers 
(ASHVE) as "a field assembled apparatus, 
comprising such elements as are necessary to 
fulfill the purpose for which it is designed, and 
serving one or more conditioned spaces. A 
factory produced unit, including all the essen- 
tial items of equipment may be employed as 
a central system." 

Although the term has been applied to most 
all types of factory produced units for han- 
dling, cooling and heating, the ASHVE desig- 
nates an "Air Conditioning Unit" as "a 
specific air treating combination consisting of 
means for ventilation, air circulation, air 
cleaning, and heat transfer with control means 
for maintaining temperature and humidity 
within prescribed limits." 

Unit Type Equipment 

These compact, factory-produced unit types 
of equipment are easy to install and assemble 
in the field, an advantage that offers consid- 



erable savings in work costs. They should 
nevertheless be conveniently located so that 
the access panels are easy to get at for in- 
spection and maintenance of the equipment. 

Be sure to follow closely the manufacturers' 
instructions for installation and operation of 
their equipment. 

The constituent parts of unitary equipment 
include the following: blowers, casings, cool- 
ing coils, drain pans, filters, heating coils, 
humidifiers, insulation, and motors. 

With a reasonable amount of maintenance, 
blowers will last as long as the unit. Keep 
the bearings properly lubricated. Oxidation 
and corrosion can be prevented by the use 
of paint with corrosion resistant properties. 

Casings may be made of sheet metal or of 
non-metallic material. They should be air 
tight and panels should be tight fitting. The 
cooling coils differ little from those found in 
central systems. 

Drain pans are generally made of heavy 
gage metal which is given a corrosion-resis- 
tant treatment. They should be inspected for 
corrosion periodically. Replace them if leaks 
are hard to locate and repair. 



284 



AIR CONDITIONING EQUIPMENT 



EQUIPMENT BASED ON LOAD FACTORS 



CAPACITY 
TONS 



MAJORITY USED 



SOME USED 



FEW USED 



Oto 5 



Unit systems in condi- 
tioned space. 



Unit central systems 
using duct distribution. 



Built up central sys- 
tems. 



5 to 25 



Built up central sys- 
tems using reciprocat- 
ing compressors. 



Unit central systems 
using duct distribution. 



Unit systems in condi- 
tioned space. 

Built up systems using 
absorption and ad- 
sorption systems. 



25 to 50 



Built up central sys- 
tems using reciprocat- 
ing compressors. 



Built up central sys- 
tems using centrifugal 
compressors. 



Central systems using 
adsorption systems. 



50 to 400 



Built up central sys- 
tems using reciprocat- 
ing compressors. 



Built up central sys- 
tems using steam jet 
and centrifugal com- 
pressors. 



400 and Over 



sys- 
tems using centrifugal 
compressors. 



Built up central sys- 
tems using steam jet. 



Note - Source: Heating Ventilating Air Conditioning Guide 1947. In addition 
to the load requirements, selection of the right equipment is based on economical 
cost elements and on local safety codes. 



The heating coils are commonly of the blast 
coil variety. For humidification, spray type, pan 
type and steam humidifiers are used. Insula- 
tion is provided for such needs as absorbing 
heat, resisting weather and vermin, and dead- 
ening sound. Motors of adequate power 
should be located where they can be reached 
for belt tightening and other maintenance. 

Remote type unit air conditioners are either 
of a vertical or a horizontal nature. Both are 
much the same in construction except for the 
location of the filters and drain pan. In some 
spray type units a pump sprays water or brine 
over the coils to wet them and to wash the 
air. Variations of these spray type units make 
use of absorbent brine solutions like lithium 
chloride or of solid adsorbents like silica gel 
to take the moisture from the air. 

In the self-contained air conditioning units 
the condensing unit and other functional ele- 
ments are combined in the same cabinet. Cool- 
ing of condensers may be by water, air or 
evaporatively. 

PREVENTIVE MAINTENANCE 

Manufacturers have prepared comprehen- 
sive manuals containing information on the 
proper handling, installation, operation and 
repair of their unitary equipment. For best 
service from the installation, therefore, be sure 
to follow carefully such instructions which 



include the correct way to prepare the equip- 
ment for use and recommended operational 
checks. 

Preventive maintenance practices are valua- 
ble in helping to anticipate and detect pos- 
sible mechanical failures. Specific time 
schedules for periodic inspections and other 
maintenance procedures depend upon local 
operating and climatic conditions. Experience, 
then, is the best authority for determining the 
frequency of these examinations for preventive 
maintenance. 

While recommended practices may vary 
according to the different makes of units, one 
manufacturer's suggestions for the seasonal 
servicing of self-contained air conditioning 
units may be of value as an example. 

Upon shutdown of these units, this company 
recommends the following: 

a. Drain all water from condenser and pip- 
ing. Blowing through the condenser with air 
under pressure helps to force out the water. 

b. Observe precautions to keep shut-off 
valve in water supply line from being turned 
on accidentally. 

c. Remove fuse from electric line if fan is 
not used while the unit is shut down. 

d. Clean surfaces of cooling coils. 

e. Flush and clean drain pan and drain 
piping. 



285 



PLANT MAINTENANCE MANUAL 




f. Inspect surfaces for corrosion. Paint rusted 
spots. 

When starting up the units again, this com- 
pany recommends the following practices: 

a. Wipe dirt and dust from exteriors of all 
components of the unitary equipment. 

b. Inspect contact points of relays, and 
dress if necessary. 

c. Replace dirty air filters. 

d. Before starting unit, observe instructions 
on proper preparation for use. 

e. After unit is operating, make necessary 
adjustments to suit the specific installation. 

Some other suggestions regarding the main- 
tenance of certain components of the equip- 
ment will be given later when discussing those 
specific parts. 

Proper diagnosis of trouble reduces repair 
time. Guides for detecting troubles are also 
available from manufacturers. 

When it comes to overhauling equipment, it 
is well to call in the manufacturer's service 
men. 

Central Systems 

The official definition of a central air con- 
ditioning system has been given previously. 

Central systems possess the advantage of 
being able to diffuse smoke and odors which 
may be present in certain areas only. Because 
of that fact the outside air requirements are 



usually more of an average nature than any 
high peak needs. An exception is, of course, 
where even weakened odors are undesirable. 
In such cases special arangements for ex- 
hausting or treating the air are usually sup- 
plied. 

Operating and maintenance costs can be 
greatly reduced by the selection of the right 
kind of system and apparatus and the proper 
installation and zoning arrangement of the 
equipment. Low maintenance costs are also 
possible where easy access to equipment has 
been provided for purposes of inspecting and 
servicing. The centralized location of most 
of the equipment also helps to make main- 
tenance easier. 

Manufacturers issue complete instructions 
on the installation, operation and care of their 
equipment. Be sure to observe such instruc- 
tions when installing and preparing equip- 
ment for use, or when starting it up and shut- 
ting it down. The right ways to check opera- 
tions and to make adjustments are also 
recommended by the makers. Some companies 
can also provide maintenance check lists for 
periodic inspections and preventive proced- 
ures both in summer and in winter operations 
and for shutting down and starting up. Always 
observe all safety precautions suggested by 
the maker regarding handling of refrigerants. 



286 



AIR CONDITIONING EQUIPMENT 




Air Cleaners 

Some means of removing dust, lint and 
other forms of air borne impurities are incor- 
porated in most, if not all, air conditioning 
systems. Cleaners are usually placed in the 
outdoor air intake ducts and in the recirculat- 
ing air ducts, and ahead of the air condition- 
ing apparatus. 

Several kinds of devices are used — filters, 
dry and viscous (adhesive); washers and scrub- 
bers; and electrostatic precipitators. 

Cleaners may be of an automatic or non- 
automatic type according to whether or not 
they are of a self-cleaning nature. 

Air Filters 

Air filters are often supplied in convenient 
units and sizes for easy handling. These unit 
filters are also simple to clean or replace, as 
may be the case. 

Automatic filters, as noted above, have 
mechanical means for removing dust and dirt. 
The non-automatic kinds may be serviced 
manually in place, or by removing them for 
cleaning. If filters are of the replaceable type, 
they are discarded when the elements become 
dirty, and new filters are installed. 

Filters should be inspected periodically, 
therefore, and cleaned or replaced according 
to their type, if cleaning is not automatic. 

Cleaning procedures for the viscous im- 
pingement filters depend upon the type of 
filter and the condition of the air borne im- 
purities being filtered. If the filters can be 
cleaned, it is common practice to use air, 



water or steam jets, or to wash them with 
kerosene ; Sometimes dipping them in oil will 
not only clean them but also supply the re- 
quired adhesive. 

Electrostatic Precipitators 

Electrostatic precipitators remove suspended 
matter in a stream of air by charging the dust 
particles electrically so that they precipitate 
by attraction to electrodes. In one non-au- 
tomatic type of electrostatic precipitator, it is 
possible to clean the plates with a water hose. 

Be sure to follow the manufacturer's rec- 
ommendations regarding the maintenance of 
their cleaning devices. 

Air Washers 

Periodic cleaning of air washers is neces- 
sary to continuous satisfactory operations. 
Operating conditions, of course, determine 
the frequency of the cleaning schedule. Un- 
der ordinary conditions, however, cleaning of 
nozzles and the tank once a week should be 
sufficient. Tanks should be drained and flushed, 
and it is advisable to brush, clean and flush 
suction screens at the same time. Caps on 
nozzles, or complete nozzles, should be re- 
placed when orifices erode or otherwise be- 
come enlarged. 

Thoroughly clean and paint the interiors of 
washers at least once a year. This procedure 
includes the surfaces of the eliminator plates, 
which should be removed for the operation. 

Where corrosive elements are present in 
the area, or where scale occurs on piping, 
in nozzles and on eliminator plates, it is well 
to check and analyze the condition of the 



287 



PLANT MAINTENANCE MANUAL 



Cleaning and 
flushing an 
air washer. 




water. If the spray water has become con- 
taminated, consult the maker of the washer 
or some other experienced adviser on the 
proper treatment of the water so that the 
equipment will not be impaired. 

Air washers are in the main enclosures in 
which air passes through a water spray for 
the purpose of cleaning, humidifying, or de- 
humidifying the air. 

The water spray may be in the form of a 
mist for contact with the air, or it may be 
sprayed on plate surfaces over which the 
air is passed. A third method is a combination 
of the other two. 

Spray washers have banks of nozzles which 
atomize the water into the air stream. This 
spraying action may be directed either along 
the line of air flow or against it, or in both 
directions at the same time. 

Scrubber type washers have eliminator-baf- 
fle plates in the air stream for deflecting its 
direction. Nozzle arrangements spray water 
on the plate surfaces. 



Air Distribution System 

Satisfactory and adequate air distribution 
is essential to a successful air conditioning 
system so that the proper comfort or indus- 
trial processing condition will be provided. 

The air distribution system comprises the air 
ducts and the necessary equipment within the 
space to be conditioned. The components are 
outside air openings, supply outlets, exhaust 
or return openings, grilles, dampers, reg- 
isters and other items. 

Supply and return openings may be per- 
forated, vaned, and slotted outlets,- ceiling 
outlets and diffusers; or perforated ceilings 
and panels. 

Duct systems should be inspected for leaks 
and corrosion, particularly at the seams and 
collars. Corroded spots should be repainted 
or otherwise repaired. Look also for conden- 
sation. 

Check the insulation; if damaged it should 
be reinforced or repaired. 




288 



AIR CONDITIONING EQUIPMENT 





111 


1 





Intakes for outdoor air should be inspected 
for clogging by debris. Look for rusting, and, 
if corroded, repaint for protection where 
necessary. 

Dampers may be adjusted manually or au- 
tomatically. If of the former type, check setting 
once in a while, and oil if desirable. If ad- 
justment is automatic, inspect linkages for cor- 
rosion. Examine blades for springing. 

Check grilles for loose dampers and for 
correct air flow. 

Automatic Controls 

Automatic controls of air conditioning sys- 
tems regulate the temperature, humidity, pres- 
sure and other functions in operating the 
equipment in the right sequence and as other- 
wise required in maintaining the desired con- 
ditions. 

These controlling instruments comprise ther- 
mostats, hygrostats, pressure regulators and 
gages, damper motors, relays, thermometers, 
automatic valves, controllers, electro-pneu- 
matic switches and other controllers. 

Make sure that the control instruments and 
connections are correct, and that they func- 
tion properly and are in accordance with the 
instructions and layouts of manufacturers who 
provide complete details regarding these 
items. 



Motors and Related Devices 

Electric motors, both a-c and d-c, are used 
for a variety of prime-moving purposes in air 
conditioning installations, as determined by 
the available power supply and the require- 
ments of the specific drive. The electrical ap- 
paratus used for starting and controlling the 
motors and for protective purposes are also 
quite varied and depend upon the types of 
motors and the desired functions. 

Motors should be inspected periodically. Be 
sure that they are properly lubricated. 

Other important points in motor mainte- 
nance are the cleaning of commutators, brush- 
es, air gaps and so forth. Inspect also motor 
starters for correct operation, and dress or 
replace contacts if desirable. Note operation 
and rating of overload protection devices. 
Chapter 3 on the maintenance of electric 
motors will be helpful in taking care of motors. 

Check belt drives for proper tension and 
readjust when necessary. Sheave alignment 
should also be watched. Protection of drives 
from oil, dirt and other foreign matter helps 
to reduce maintenance costs and work. 

Clearances of flexible couplings should 
also be checked from time to time to see that 
shafts have not been bent or thrown out of 
line. 



289 



PLANT MAINTENANCE MANUAL 



Fans 

Two basic types of fans found in air con- 
ditioning and ventilating systems are the 
axiai flow, or propeller, type and the radial 
flow, or centrifugal, type. There are varying 
designs of each of these. 

Factors which determine the type, design 
and size of the fans are the desired perform- 
ance, efficiency, nature of load, amount of 
air to be moved and limitations of space, 
noise, power and the like. Fan efficiency, in- 
cidentally, is "the ratio of the horsepower out- 
put to the horsepower input." 

Fans are also designated by the direction 
of rotation — clockwise or counterclockwise. 
Discharge may be top horizontal, bottom hori- 
zontal, up blast and down blast. 

Good solid foundations are important to 
the long life and satisfactory operation of fans 
whether they are large or small. Proper align- 
ment is also essential. Where large fans re- 
quire special foundations, the manufacturer 
supplies drawings or other specific instructions 
for installation. 

Like all other equipment, fans are in first 
class condition when shipped. Sometimes in 
transit, however, they are subject to rough 
handling. It is advisable, then, to inspect for 
damage to the fan and to its balance. Manu- 
facturers supply complete instructions for fan 
balancing, if it is necessary. 

Checking and Cleaning 

The collection of dust, dirt and grease on 
rotors or blades can affect fan balance and 
performance. It is well then to clean fans 
periodically. Cleaning can be accomplished 
in several ways — with wire brush, scraper, 
hose or compressed air. The amount of dirt in 
the air determines the frequency of cleaning. 

Fan wheels, blades and rotors should be 
checked for wear at the same time they are 
cleaned. Badly worn fans should be repaired 
or replaced. 

It is also advisable to clean and paint the 
exterior and interior parts of fans and their 
housings at the regular inspection and clean- 
ing periods. This practice will prolong the life 
of the equipment, especially if corrosive con- 
ditions prevail in the location. 

Be sure that fan bearings are properly lu- 
bricated. Use only the kind and grade of lu- 
bricant recommended by the maker. The chap- 
ter on both sleeve bearings, No. 12, and anti- 
friction bearings, No. 13, describe the proper 
practices for the care of those two basic kinds 
of bearings. 

If fans vibrate, the units should be checked 



for the cause. Among the parts to check are 
alignment, fastenings, bearings, balance of 
fan. 

Inspect bearings, shafts, drives, and coup- 
lings, etc., for alignment. 

REFRIGERATION 

Most air conditioning systems require some 
artificial means of cooling air in the summer- 
time. 

Two common classifications of refrigeration 
equipment are steam ejector and mechanical 
compression. Absorption machines are also 
used, but to a lesser degree than the other 
two. 

Refrigerants used are ammonia, carbon di- 
oxide, methyl chloride, dichlorodifluorometh- 
ane, monochlorodifluoromethane, monofluoro- 
trichloromethane, and water. Fortunately the 
tongue twister compounds mentioned above 
commonly go under various trade names that 
are much easier to pronounce and spell. Be 
sure to use only the refrigerant specified by 
the manufacturer of the machines. 

The steam ejector, or steam jet, system em- 
ploys water vapor as the refrigerant and 
steam jet power is used for compressing it— 
the process being vaporization of water un- 
der high vacuum at low temperatures. 

Compressors and Condensers 

Compressors used in the mechanical com- 
pression of refrigerants are of two main types: 
reciprocating and centrifugal. They are also 
classed according to whether they are open 
or enclosed. Electric motors are a very com- 
mon form of prime mover for compressors. 
However, modern steam, gas and oil engines 
may be employed. Drives are usually of belt 
or direct connection. 

Since the various makes of compressors 
usually require different techniques for their 
maintenance and repair, it is 'best to refer to 
the manufacturers for instructions on the care 
and servicing oi their equipment. 

Condensers may be air cooled, water 
cooled or cooled by a combination of air 
and water. The last named is called an eva- 
porative condenser. 

In the usual air cooled condenser, a fan 
blows air across the surface coil to cool 
and condense the hot gas. 

There are three forms of water cooled con- 
densers—the shell and tube, shell and coil, 
and double pipe. In the shell and tube design 
the tubes carry the condenser water while 
the refrigerant is cooled in the shell outside 
the tubes. In the shell and coil, the condensing 



290 



AIR CONDITIONING EQUIPMENT 



I* 1 .•«i-v..<iw!i"r 




Leak detector 
for checking 
for leaks . 



water also flows through the coil which is 
mounted inside a shell which contains the 
refrigerant. In double pipe condensers there 
are two concentric pipes, the condenser water 
flowing through the inner pipe while the re- 
frigerant is condensed in the outer surround- 
ing pipe. 

Coolers may be of the direct or indirect 
type. In the first case either the water or the 
air is cooled directly. The indirect method is 
to use brine, which has been cooled by the 
refrigerant, to cool the air or water. 

Two common ways to cool spray water are 
by letting it spray or flow over the expansion 
coils which are installed in the chamber. 

Maintenance 

Refrigeration equipment should be serviced 
in winter time. After extended shutdowns, 
compressors should be checked to see that, 
for instance, the shaft seal is still tight and is 
sufficiently lubricated before admitting the re- 
frigerant to the receiver. 

Check drive motors, starters and overload 
protective devices for satisfactory operation. 

Water regulating valves should be ex- 
amined for correct working. Make sure that 
the valve stem does not stick and if valve seats 
are worn, replace them. 

Water cooled condensers should be clean- 
ed of scale and other dirty foreign substances 
before starting up coofing operations. Any 



air or gas accumulations should also be 
cleared out. 

Evaporative condensers should be cleaned 
frequently. The parts to be cleaned are pans, 
coils, water strainers, and the like. Condens- 
ing coils may also require clearing out. 

Keep motor and fan bearings lubricated 
properly. 

Inspect valves, oiling systems, pistons and 
rings, and cylinders for wear. Replace or re- 
pair as required. 

Humidifying and Dehumidifying 

Air is humidified by vaporizing water, heat 
being required in the process. Humidification 
then is the adding of water vapor to the air. 
Conversely, dehumidiflcation is the' reduction 
of the water vapor in the air, in which pro- 
cess heat may or may not be removed. 

Humidification can be accomplished in sev- 
eral ways: indirectly by the air washer or di- 
rectly by spraying water or by steam jets. 
One or both of these latter methods may be 
used. 

Air washers, or humidifiers as they are often 
called, are also commonly used in ventilating 
work and have been discussed elsewhere. Air 
washers, incidentally, can also be used as 
dehumidifiers— the different effects being ob- 
tained by different water temperatures and 
methods of operation. 

Dehumidiflcation is also obtained through 



291 



PLANT MAINTENANCE MANUAL 



the use of sorbent materials. These materials 
may be absorbent or adsorbent. The former 
kind, which changes physically or chemically, 
or both, during the process, includes the solid 
calcium chloride and the liquids of lithium in 
both chloride and bromide forms and calcium 
chloride. Adsorbent materials, which do not 
change physically or chemically in the sorb- 
ent process, are silica gel, activated alumina 
and the like. 

Preheating and Reheating 

Preheating coils are used to heat air before 



it passes through the water spray so as to 
increase the ability of the air to pick up moist- 
ure. 

Reheating coils are used to raise the tem- 
perature of the air leaving the washer to 
either that of the room or to that necessary to 
offset the room heat loss. Sometimes booster 
coils are placed in ducts to regulate the tem- 
perature of the air. 

By-pass pipes or ducts are provided where 
it may be desired to pass air around an ele- 
ment of the system, like a coil, humidifier, con- 
ditioner, etc. 




292 



INDEX 



Air compressor equipment, 258-269 

accessories, 263 

air consumption, 259 

air distribution, 260, 268-269 

air pressure, 260, 264, 268, 269 

bearings, 262, 263 

blowers, 262 

capacity, compressor, 259, 266-267 

centrifugal compressors, 262-263 

cleaning, 261, 262, 263, 265 

Compressed Air and Gas Institute, 258 

Compressed Air Handbook, 258, 266 

exhausters, 262-263 

inspections, 262; 263 

installation, 258-259, 260, 261, 262-263 

kinds, 258, 261 

leakage, 258, 268 

location, 260, 261 

low air pressure, 259, 268-269 

lubrication, 261, 262, 263, 264-265 

operating difficulties, symptoms, 263 

portable tools, 264-269 

reciprocating compressors, 261-262 

rotary compressors, 262 

service hints, 260 
Air conditioning equipment, 281-292 

advantages, 281 

air distribution systems, 288-289 

American Society of Heating and VentilaMng 
Engineers, 282, 284 

automatic controls, 289 

central systems, 286-290 

classifications of systems, 282, 284, 285 

cleaners, air, 287 

cleaning, 287, 290, 292 

compressors, 290-291 

condensers, 290-291 

definitions, 281-282 

dehumidifkation, 291-292 

electrostatic precipitators, 287 

fans, 290 

filters, air, 287 

heating coils, 292 

Heating, Ventilating, Air Conditioning Guide of 
ASHVE, 282, 283, 285 

humidification, 291-292 



Air conditioning equipment (continued) 

humidities, 281, 283 

inspections, 285-291 

installation, 284, 285, 286 

motors, 289 

refrigeration, 290-292 

temperatures, 281, 283 

unit type equipment, 284-286 

washers, air, 287-288 
American Gear Manufacturers Association, 111, 112, 

114, 119 
American Leather Belting Association, 76, 77-79 
American Society for Testing Materials, 204 
American Society of Heating and Ventilating 

Engineers, 270, 275, .282, 284 
American Standards Association, 11, 39, 96, 98, 276 
American Wood Preservers' Association, 205 
Anti-friction bearings, 129-137 

Anti-Friction Bearing Manufacturers Association, 129 
Arbor press, 134, 135 

Associated Factory Mutual Fire Insurance Companies, 
11, 245 



B 



Babbitted bearings, 121, 123-124 
Ball and roller bearings, 129-137 

Anti-Friction Bearing Manufacturers Association, 129 

arbor press, 134, 135 

cleaning, 129, 132, 133, 134 
construction, 129, 130-131 
defects, for rejection, 136, 137 
dirt, damage from, 132 
handling, 129, 132, 136 
inspections, 136, 137 
installation, 134-135 
load transmission, 131 
lubrication, 136 
mounting, 135 
pullers, 134 
removal, 134-135 
storage, 129, 136 
types, 129, 130-131 
Bearings 
air compressor, 262, 263 
ball and roller, 129-137 
electric motor, 25-28 



293 



INDEX 



Bearings (continued) 

electric tool, 33 

plain, 120-128 

pump, 218, 220 

sleeve, 120-128 
Belts 

conveyor, 163-168, 174-176 

leather, 73-84 

power transmission, 73-84, 85-95 

rubber, 85-95 

V-belts, 91-95 
Block chains, 100 
Bushings, 120 



Controllers, electric, 48-60 
Conveyors 

belt, 163-168, 174-176 

bucket elevators, 172 

chain, 168-169 

chute, 163 

continuous flow, 172 

gravity, 163 

industrial, 160-172 

monorail, 170 

overhead systems, 168-170 

pneumatic, 170, 171 

portable, 173-184 

roller and wheel, 160-163, \76, 178 

tramrail, 170 
Conveyor chains, 100 



Chain and electric hoists, 148-159 

applications, 151-152, 157-159 

chain hoists, 148-152 

cleaning, 157 

construction, 148, 149, 154 

designs, 148, 153 

electric hoists, 153-159 

differential hoist, 148, 150 

highlights, 148 

inspections, 148-149, 150, 156-157 

lubrication, 150, 157 

operation, 155-156 

safety, 155-156 

screw gear hoist, 148, 150 

spur gear hoist, 148, 149, 150 

types, 148, 153 

worm gear hoist, 148, 150 
Chain drives (See Transmission chains) 
Circuit breakers 

air, 64-66 

oil, 66-69 
Cleaning 

air compressor equipment, 261-263, 265 

air conditioning equipment, 287, 290, 292 

ball and roller bearings, 129, 132-134 

chain and electric hoists, 157 

electric motors, 26-28 

electric tools, portable, 36-37 

floors, 203, 205, 207-209 

gear drives, 112 

heating equipment, 271-273, 279 

industrial controls, 53 

industrial conveyors, 163, 167, 170 

leather belts, 82 

lighting equipment, 1, 4-5 

plain bearings, 122, 123 

pumps, 212, 220 

roofs, 200 

rubber belts, 90 

switching equipment, 62 

transmission chains, 106 

traps and strainers, 239, 241, 244 

valves, 228 

wire rope, 144 
Compressed Air and Gas Institute, 258 
Compressed Air Handbook, 258, 266 
Conductors (See Industrial wiring) 



Definitions of Terms 

air conditioning, 281-282 

lighting equipment, 1-2 

pumps, 211 

switching equipment, 61 

transformer^, 39-40, 41 
Distribution systems 

air, 260, 268-269 

wiring, 10 



Electric controls, 48-60 

Electric hoists, 153-159 

Electric Industrial Truck Association, 196 

Electric motors, 20-28 

bearings, 22, 25-28 

cleaning, bearings, 26-28 

conductors in conduit, 22 

data cards, 28 

inspection schedule, 23-24 

installation, 21 

location, 21 

lubrication, 25-26 

National Electrical Code, 22 

recent improvements, 20 

rotation, 21 

selection, 21 

servicing, 24-28 

supply line and controls, 21 

wire and conduit sizes, 22 
Electric tools, portable, 29-37 

bearings, 33 

brushes and commutators, 33, 36 

cables, 33 

care and use, 32 

chucks, 36 

cleaning, 36-37 

constructional details, 34-35 

electro-magnet motivation, 30 

grounding, 32 

heating of motor, 33 

high cycle motors, 29-30, 32 

inspections, 32 



294 



NDEX 



Electric toots, portable (continued) 

kinds, 30, 31 
, lubrication, 37 

power, 29-30 

proper usage, 32-33 

shorting, 36 

switches, 33 

trouble shooting, 36 

universal motors, 29, 32 
Electrical equipment and apparatus 

controls, 48-60 

lighting, 1-8 

motors, 20-28 

portable tools, 29-37 

switchgear, 61-72 

transformers, 38-47 

wiring, 9-19 
Efevators 

bucket, 172 

portable, 178-184 



Factory Mutual Laboratories, 245 
Fire extinguishers, 245-257 

anti-freeze, 252 

bucket tanks, 247-248 

colcium chloride solutions, 248 

carbon dioxide, 257 

dry chemical, 256 

extinguishers to use, 246 . 

fire classifications, A, B, C, 246 

fire protective agencies, 245 

first aid fire protection, units of, 245, 248-257 

foam, 254 

inspections, 247, 248-257 

kinds of fires, 245-246 

loaded stream, 253 

pump tanks, 249 

servicing, 247, 248-257 

soda and acid, 251 

vaporizing liquid, 255 

water pails and barrels, 247-248 

water type, gas cartridge, 250 
Floors. 203-209 
Friction, 120, 129 
Fuses, 58, 71 



Gear boxes and cases, 108-119 
Gear drives, 108-119 

alignment, 111 

American Gear Manufacturers Association, 111, 
112, 114, 119 

cleaning, 112 

enclosed drives, 110-115 

foundations, 110-111 

inspections, 116-117, 119 

installation, 110-111 

kinds, 108, 109 

lubricants, recommended, 113-115, 118 

lubrication, 111-115, 118-119 



Gear drives (continued) 

open gear drives, 112-113, 115, 118-119 

operation, 110 

selection, 108 

storage, 112 

temperatures, lubricant, 112-113 

tooth wear and failure, 116-117, 119 

viscosity range, lubricant, 113 



H 



Heating equipment, 270-280 

American Society of Heating and Ventilating 
Engineers, 270 

boilers, 271, 277 

boiler tubes, 271 

cleaning, 271-273, 279 

condensers, 279 

direct-fired types, 276 

electric unit heaters, 276 

heating coils, 279 

hot water type, 275 

inspections, 271-273, 278 

installation, 275, 276 

kinds, 270, 274 

location, 276-277 

lubrication, 271, 272 

piping arrangements, 277 

power plant, 270-273 

steam type, 275 

unit heaters, 274-280 
Heating, Ventilating, Air Conditioning Guide, 282, 
283, 285 



Illuminating Engineering Society, 8, 11 
Industrial controls, 48-60 
accessories, 49 
adjustment, 51 
arc boxes and chutes, 58 
cleaning, 53 
connections, 60 
contacts, 55-56 
controllers, 48 
fuses, 58 

inspections, 52, 54, 55 
installation, 51 
interlocks, 57 
magnets and coils, 56-57 
National Electrical Manufacturers Association, 

48, 49, 51 
protection, 48-49 
rectifiers, 58 
relays, 58-59 
nesistors, 59 
safety, 48-49 

selection of equipment, 49 
service conditions, unusual, 49-50 
shunts, 57 
starting motors, 49 
switches, 59 
transformers, 59 
trouble shooting, 53, 56-60 
wiring, 60 



295 



INDEX 



Industrial conveyors, 160-172 

belt, 163-168 

bucket elevators, 172 

canvas belts, 164 

chain conveyors, 168-169 

chutes, 163 

cleaning, 163, 167, 170 

continuous flow, 172 

gravity, 163 

idlers. 166-167 

inspections. 162-163, 166 

installation, 164 

joining belt ends, 164 

kinds, 160 

loading, 165 

lubrication, 162-163, 169 

monorail, 170 

overhead systems, 168-170 

pneumatic, 170, 171 

repairing belts, 164, 165 

roller, 160-163 

rubber belts, 163 

storage, 168 

tension, belt, 164-165 

tramrail, 170 

trouble shooting, belt, 166 

wheel, 160-163 
Industrial power trucks, 185-197 

batteries, storage, 195-197 

brushes and commutators, 195 

charging batteries, 195-196 

clearances, 186 

Electric Industrial Truck Association, 196 

electric power, 185. 194. 195 

floor conditions, 186, 189 

gas power, 185, 193 

handling systems, 188-189 

inspections, 191-194 

kinds, 185, 188-189 

lift trucks, 188, 189 

lubrication, 191, 192 

motive power, 185 

motorized hand trucks, 188 

operation, economical, 186, 190 

operators, training, 186 

pallets, 189 

safety precautions, 197 

skids, 188, 189 

speeds, 186 

tire saving, 191 

tractor-trailers, 188 
Industrial Unit Heater Association, 275 
Industrial wiring, 9-19 

adequate wiring, 11 

conductors, 12-15, 17-18 

current carrying capacities, 14, 15, 17, 18 

distribution systems, 10 

flexible cords, 18-19 

hazardous locations, 16 

inspections, 10, 16 

installation factors, 9-10 

insulation, 12-13 

materials, 14-15, 18 

methods, 14-15, 18 



Industrial wiring (continued) 

National Electrical Code, 10, 11, 12-18 

overheating, 16 

safe procedures, 10-11 

splices, joints and taps, 17-18 

trouble shooting, 16 
Industry Committee on Interior 

Wiring Design, 11 
Inspections 

air compressor equipment, 262, 263 

air conditioning equipment, 285-291 

ball and roller bearings, 136, 137 

chain and electric hoists, 148-149, 150, 156-157 

electric motors, 23-24 

gear drives, 116-117, 119 

heating equipment, 271-273, 278 

industrial controls, 52, 54, 55 

industrial conveyors, 162-163, 169 

industrial wiring, 10, 16 

lighting equipment, 1 

plain bearings, 122, 123 

portable conveyors and elevators, 173 

portable electric tools, 32 

power trucks, 191-194 

pumps. 212, 218, 220, 221 

roofs, 200, 201, 202 

switching equipment, 62-63, 65-67, 69-72 

transformers, 41-42, 44-45, 47 

transmission chains, 100, 101, 106 

traps, 239, 241 

valves, 229 

wire rope, 145-146 
Installation 

air compressor equipment, 258-263 

air conditioning equipment, 284-286 

ball and roller bearings, 134-135 

conveyors, industrial, 164 

electric motors, 21 

elevators, portable, 180 

floors, 203-205 

gear drives, 110-111 

heating equipment, 275, 276 

industrial controls, 51 

industrial wiring, 9-10 

leather belts, 80-81 

lighting equipment, 2 

plain bearings, 122-125 

pumps, 210-212 

roofs, 198-199 

rubber belts, 89, 94, 95 

switching equipment, 62 

transformers, 41-42 

transmission chains, 100, 102-103 

traps, 239 

valves, 227 
Interlocks, 57, 71, 72 



Lamps (See Lighting equipment) 
Leather belts, 73-84 

alignment, 82 

American Leather Belting Association, 76, 77-79 



296 



INDEX 



Leather belts (continued) 

cleaning, 82 

construction, 73-75 

design, 76 

dressing, 75, 83 

endless, 75 

engineering, 76-80 

fasteners, 81, 83 

horsepower rating, 78-80 

installation, 80-81 

lacing, 80-81 

laps, 83 

ordering data, 77 

pulleys, 76. 77, 79, 81, 84 

running direction, 81 

service factors, 80 

short center drives, 76 

sizes, 76, 77 

tension, 81 
Lighting equipment, 1-8 

access to fixtures, 1, 7 

application of types, 3 

cleaning, 1, 4-5 

filament lamps, 2, 3, 6 

fluorescent fixtures, 2, 3, 6 

fundamentals, 2 

Illuminating Engineering Society, 8 

illuminating terms, 1-2 

inspections, 1 

installations hints, 2 

lamp life, 4 

lamp replacements, 4 

levels of illumination, 8 

light output, 1 

mercury fixtures, 3, 6 

reaching equipment, 7 

trouble shooting, 6 

types of lamps, 3 
Lubrication 

air compressor equipment, 261-265 

ball and roller bearings, 136 

chain and electric hoists, 150, 157 

conveyors, industrial, 162-163, 169 

electric motors, 22, 25-26 

gear drives, 111-115, 118-119 

heating equipment, 271, 272 

plain bearings, 120, 123, 125-128 

portable conveyors and elevators, 173-175, 178, 
180, 182-183 

portable electric tools, 37 

power trucks, 191, 192 

pumps, 218, 220 

switching equipment, 64 

transmission chains, 103-104, 106 

valves, 232 

wire rope, 144 



M 



Materials handling equipment 

hoists, chain and electric, 148-159 

industrial conveyors, 160-172 

portable conveyors and elevators, 173-184 



Materials handling equipment (continued) 

power trucks, industrial, 185-197 

wire rope, 138-147 
Meters, 71, 72 
Motors, 20-28, 29-30, 49 

N 

National Board of Fire Underwriters, 11, 245 
National Electrical Code, 10-11, 12-18, 22, 32, 61 
National Electrical Manufacturers Association, 11, 

38-40, 42-45, 48, 49-50, 61, 69, 70 
National Fire Protection Association, 10, 11, 245 



Oil (See a/so Lubrication) 
circuit breakers, 66-69 
transformer, 42-44 



Panelboards, 61-64 
Plain bearings, 120-128 

adjustment, 123 

babbitt, 121, 123-124 

cadmium base, 121 

cleaning, 122, 123 

clearances, 122-123 

copper base, 121 

copper-lead, 121 

fitting and scraping, 124-125 

graphited, 126, 127 

greasing, 126 

grooving, 126, 127 

inspections, 122, 123 

lead base, 121 

lubrication, 120, 123, 125-128 

materials, 120-122 

oiling, 125-126, 127-128 

plastic, 121 

self lubricating, 121-122 

solid lubricants, 126 

temperatures, 123 

tin base, 121 

water lubrication, 126-127 
Plant equipment 

air compressor, 258-269 

air conditioning, 281-292 

floors, 203-209 

fire extinguishers, 245-257 

heating equipment, 270-280 

pumps, 210-221 

roofs, 198-202 

traps and strainers, 233-244 

valves, 222-232 
Portable conveyors and elevators, 173-184 

belt, 174-176 

cable care, 181 

cable controls, 180 

clips, cable, 181, 184 

conveyors, 173-178 

drum end plug, cable, 184 

elevators, 178-184 

hydraulic system, 181 



297 



INDEX 



Portable conveyors and elevators (continued) 
inspections, 173 
installation, 180 
kinds, 176-179 

lubrication, 173-1*75, 178, 180, 182, 183 
motor care, 174, 180 
replacements, 184 
roller, 176-178 
tracking belts, 176 
Portable tools 

compressed air, 264-269 
electric, 29-37 
Power plant, 270-273 
Power transmission equipment 

ball and roller bearings, 129-137 
gear drives, 108-119 
leather belts, 73-84 
plain bearings, 120-128 
rubber belts, 85-95 
transmission chains, 96-107 
Power trucks, 185-197 
Preformed wire rope, 138 
Pullers, bearing, 134 

Pulleys, 76, 77, 79, 81, 84, 87, 89, 92, 94 
Pumps, 210-221 
bearings, 218, 220 
centrifugal, 214-216, 217-218 
cleaning, 212, 220 
definition of terms, 211 
diffuser, 217 

inspections, 212, 218, 220, 221 
installation, 210-211, 212 
kinds, 210, 211, 213 
lubrication, 218, 220 
materials, 210 
mixed flow, 217 
priming, 212 
propeller, 217 

reciprocating, 214-216, 219-220 
rotary, 214-216, 220-221 
selection, 210-211 
trouble shooting, 214-216 
volute, 217 



Rectifier, 58 

Relays, 58-59, 69-70 

Resistors, 59 

Roller bearings, 129-137 

Roller chain drives, 98 

Roofs and floors, 198-209 
absorbent compounds, 209 
asbestos shingles, 198 
asphalt, 198, 203, 207 
asphalt tile floors, 207 
built-up roofs, 198-200, 202 
cleaning, 200, 203, 205, 207-209 
concrete floors, 203-204, 208 
critical areas of roofs, 201 
damage repair, roofs, 200, 202 
defects, roofs, 200, 202 
flat roofs, 198 



Roofs and floors (continued) 

floors, 203-209 

inspections, 200, 201, 202 

installation, 198-199, 203, 204, 205 

linoleum floors, 207, 209 

mastic floors, 206-207, 209 

materials, 198-199 

metallic roofs, 198 

pitch, 198 

roofs, 198-202 

specifications, roof, 199 

surfacing, roofs, 198 

wood floors, 203, 208 

wood block floors, 205-206, 208 
Rubber belts, 85-95 

alignment, 90 

cleaning, 90 

construction, 85-86, 91-92 

dressing, 90 

engineering, 87-88, 92-93 

fasteners, 89, 90 

flat, 85-90 

formulas, useful, 88, 93 

installation, 89, 94, 95 

power transmission, 87 

pulleys, 87, 89 

putting on, 89, 94 

removing, 90 

rotation, 89 

sheaves, 92, 94 

sizes, 87, 93, 94 

storage, 90 

tension, 87, 89, 90, 92, 95 

types, 86, 91-92 

V-belts, 91-95 



Safety procedures 

chain and electric hoists, 155-156 

industrial controls, 48-49 

industrial wiring, 10-11 

power trucks, 197 

switching equipment, 61, 67 

transformers, 40, 42 

transmission chains, 106 

wire rope, 139, 143, 147 
Sheaves, 92, 94 
Silent chain drives, 99-100 
Society of Automotive Engineers, 103, 121, 122 
Speed reducers, 108-119 
Sprockets, 98, 99-100 

Steam Trap Manufacturers, Special Committee of, 241 
Storage 

ball and roller bearings, 129, 136 

conveyors, industrial, 168 

gear drives, 112 

rubber belts, 90 

transformers, 41 

transmission chains, 107 
Storage batteries, 195-197 
Strainers, 237, 244 
Switches, 33, 59, 70-71 

(See a/so Switching equipment) 



298 



NDEX 



Switchboards, 61 
Switchgear, 61-72 
Switching equipment, 61-72 

bus and connection bars, 72 

circuit breakers, 64-66, 66-69 

circuit grounds, 64 

cleaning, 62 

condensation, 64 

electrical checks, 69 

fuses, 71 

inspections, 62-63, 65-67, 69-72 

installation, 62 

interlocks, 71, 72 

lubrication, 64 

meters, 71, 72 

National Electrical Code, 61 

National Electrical Manufacturers Association, 
61, 69, 70 

panelboards, 61-64 

relays, 69-70 

safety, 61, 67 

switchboards, 61 

switches, 70-71 

temperatures, 63-64 

transformers, 71, 72 

trouble shooting, 68, 70, 71 



Transformers, 38-47, 59, 71, 72 

cooling and insulating materials, 43-44 

definitions, 39-40, 41 

distribution type, 41-47 

drying out, 42 

failure, 42-43 

filling, 44 

filter press, 45 

handling, 41 

inspections, 41-42, 44-45, 47 

installation, 41-42 

kinds, 38-39, 41, 45 

liquid, checking, 43 

mounting, 41 

National Electrical Manufacturers Association, 
38, 39, 40, 42-45 

oil, sampling and testing, 43-44 

performance, 40 

polarity, 40 

ratings, 40 

safety, 40, 42 

specialty, 38-39 

storage, 41 

successful operation, 39 

taps, 40 

trouble shooting, 46 

windings, 40 
Transmission chains, 96-107 

adjustment, 102-103 

alignment, 100, 102 

block chains, 100 

calculating chain lengths, 97 

casings, 106 

checks, periodic, 106 

cleaning, 106 



Transmission chains (continued) 

connecting ends, 102 

construction, 98-100 

conveyor chains, 100 

inspections, 100, 101, 106 

installation, 100, 102-103 

kinds, 98 

lengthening chains, 103 

lubrication, 103-104, 106 

repairing, 103 

roller chains, 98 

safety, 106 

selecting the drive, 96-97 

shortening chain, 103 

silent chains, 99-100 

sprockets, 98, 99-100 

storage, 107 

trouble shooting, 101 
Traps and strainers, 233-244 

air venting, 240, 241 

applications, 233 

bucket traps, 235 

by-pass arrangements, 239 

cleaning, 239, 241, 244 

flash steam, 240 

float traps, 236 

float and thermostatic, 236 

impulse traps, 237 

inspections, 239, 241 

installation, 239 

kinds, 233-234 

lapping parts, 240 

passing steam, 240 

pipe connections, 239 

priming, 240 

seats, 241 

selection, 238 

steam pressures, 240 

strainers, 237, 244 

testing, 240 

thermostatic traps, 234 

trouble shooting, 242-243 
Trouble shooting 

conveyors, belt, 166 

industrial controls, 53, 56-60 

industrial wiring, 16 

lighting equipment, 6 

portable electric tools, 36 

pumps, 214-216 

switching equipment, 68, 70, 71 

transformers, 46 

transmission chains, 101 

traps, 242-243 



u 



Underwriters Laboratories, Inc., 245 
Unit heaters, 274-280 



Valves, 222-232 
angle, 223, 225 
bonnet joints, 223, 224 



299 



INDEX 



Valves (continued) 
check, 223, 226 
cleaning, 228 
end connections, 222 
failure, 229 
gate, 223, 224 
globe, 223, 225 
inspections, 229 
installation, 227 
kinds, 222, 223 
leaks, 229, 230 
location, 227 
lubrication, 232 
materials, 222 
operation, 223 
packing, 230 
records, 230 

regrinding seats, 230, 231 
seats, 230, 231 
stems and spindles, 223, 224 
stuffing boxes, 230 
supports, 227 
threading pipe, 228 
tightening joints, 229 



w 



Wire and cable conduit sizes, 14, 15, 17, 18, 22 
Wire rope, 138-147 

abrasion, 139, 140, 146 

bending fatigue, 140 



Wire rope (continued) 

calculations, 146 

cleaning, 144 

clips, attaching, 143 

construction, 138-139 

cores, 139 

corrosion, 139 

cutting, 145 

drums and sheaves, 139, 145 

Filler wire, 140 

handling, 141 

heat, 139 

injuries, causes, 145-146 

inspections, 145-146 

lays, 139 

loads, 139 

lubrication, 144 

materials, 140 

preformed, 138 

rope grades, 139 

safety slings, 143 

Seaie wire, 140 

seizing, 141-142 

selection, 139 

serving, 141-142 

slings, 143, 147 

sockets, attaching, 142-143 

structure, 138-139 

unreeling and uncoiling, 141 

Warrington wire, 140 
Wiring, 9-19, 60 

(See Industrial wiring) 



300 



A^uM Date Due 


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